SANAA, Yemen (AP) -- One of several Americans held by Iranian-backed Shiite rebels in Yemen was set free on Monday, a U.S. official said, as a French hostage abducted in Yemen by an unknown party appeared in a video pleading for help.
The rebels, known as Houthis, seized the capital last year and have been the target of a U.S.-backed and Saudi-led air campaign since March 26. The deal to release the American, who was not immediately identified, was mediated by Oman.
The released American, who had been injured in unknown circumstances, was on his way to Oman, according to the U.S. official, who was not authorized to publicly discuss the matter because of privacy rules and spoke on condition of anonymity. No details on the identity of the freed captive were immediately available.
A video meanwhile surfaced showing Frenchwoman Isabelle Prime, a World Bank consultant who was kidnapped in February, pleading for help. The Associated Press viewed the video on Monday.
Yemen conflict, May/June, hostage, Isabelle Prime
American held in Yemen freed; French hostage pleas for help
Yemeni members of the southern separatist movement, loyal to President Abedrabbo Mansour Hadi, gather around a car on June 1, 2015 in Aden's northern suburbs. A UN-chartered ship loaded with humanitarian supplies bound for Yemen was targeted by shelling as it approached the country's main southern port of Aden on Sunday, an official said. (Photo credit Saleh Al-Obeidi, AFP/Getty Images)
Smoke billows following an air-strike by Saudi-led coalition on June 1, 2015, in the Yemeni capital Sanaa. The raid targeted an arms depot in the Mount Noqum area on the eastern outskirts of Sanaa. (Photo credit Mohammed Huwais, AFP/Getty Images)
Yemeni members of the southern separatist movement, loyal to President Abedrabbo Mansour Hadi, stand next to a tank on June 1, 2015 in Aden's eastern suburbs. A UN-chartered ship loaded with humanitarian supplies bound for Yemen was targeted by shelling as it approached the country's main southern port of Aden on Sunday, an official said. (Photo credit Saleh Al-Obeidi, AFP/Getty Images)
A Huthi Shiite militant inspects what remains of a hotel destroyed in an air-strike by the Saudi-led coalition on May 31, 2015 in Al-Thawra sport city located north of the capital Sanaa. Human Rights Watch published new evidence alleging a Saudi-led coalition is using internationally banned cluster bombs in Yemen, urging it to stop such attacks that were harming civilians. (Photo credit Mohammed Huwais, AFP/Getty Images)
Armed militiamen loyal to Yemen's fugitive President Abderabbo Mansour Hadi sit at the back of a pick up truck during ongoing clashes with opponents and Huthi rebels in the port city of Aden's Dar Saad suburb on May 28, 2015. (Photo credit Saleh Al-Obeidi, AFP/Getty Images)
Yemeni children inspect the rubble following an air-strike by the Saudi-led coalition on May 31, 2015 in Al-Thawra sport city, located north of the capital Sanaa. Human Rights Watch published new evidence alleging a Saudi-led coalition is using internationally banned cluster bombs in Yemen, urging it to stop such attacks that were harming civilians. (Photo credit Mohammed Huwais, AFP/Getty Images)
Smoke billows following an air-strike by the Saudi-led coalition on the headquarters of the Special Security Forces, formerly known as the Central Security, on May 27, 2015, in the Yemeni capital Sanaa. Saudi-led coalition warplanes bombed rebel troop headquarters in the Yemeni capital in strikes that killed 36 soldiers, witnesses and a health official said. (Photo credit Mohammed Huwais, AFP/Getty Images)
Yemenis inspect the rubble of destroyed houses in the Dar Saad neighbourhood of the southern Yemeni city of Aden, on May 26, 2015, a day after rebel forces and loyalist fighters were locked in fierce fighting. (Photo credit Saleh Al-Obeidi, AFP/Getty Images)
Yemeni workers unload medical aid boxes from a boat carrying 460 tonnes of Emirati relief aid that docked in the port of the city of Aden, on May 24, 2015. The shipment, including medical and food supplies, is the second from the United Arab Emirates, which delivered last week 1,200 tonnes of relief aid. (Photo credit Saleh Al-Obeidi, AFP/Getty Images)
Armed Yemeni tribesmen from the Popular Resistance Committees, supporting forces loyal to Yemen's Saudi-backed fugitive President Abedrabbo Mansour Hadi, monitor an area near Sirwah, in the west of Marib province, east of the capital, Sanaa on May 21, 2015 as they continue to battle Shiite Huthi rebels. A United Nations conference to relaunch political talks on Yemen will open in Geneva next week, a UN spokesman said on May 20, despite uncertainty over who will attend. (Photo credit AFP/Getty Images)
Smoke billows following an air-strike by the Saudi-led coalition on an army arms depot, now under Shiite Huthi rebel control on May 22, 2015 east of the Yemeni capital Sanaa. The Saudi-led coalition has waged an air campaign against the Huthis since March 26 in an effort to restore the authority of Hadi, who has fled to Riyadh with members of his government. (Photo credit Mohammed Huwais, AFP/Getty Images)
A Yemeni woman stands atop the rubble of houses destroyed by Saudi-led air strike on a residential area last month, in the capital Sanaa, on May 18, 2015. Saudi-led coalition warplanes resumed strikes on rebel positions in southern Yemen after a five-day ceasefire expired, jeopardising efforts to deliver desperately needed aid. (Photo credit Mohammed Huwais, AFP/Getty Images)
Armed Shiite Huthi rebels battling supporters of Yemen's Saudi-backed President Abedrabbo Mansour Hadi mans a tank on May 14, 2015 as they try to enter the Mansoura district of the southern Yemeni port city of Aden from the northern farmland and suburbs they control. The Saudi-led coalition against Huthi rebels in Yemen warned on May 14 a five-day truce 'would not last long' in the face of alleged breaches, as the UN called for calm to allow badly needed aid to reach the country. (Photo credit Mohammed Huwais, AFP/Getty Images)
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Prime was abducted in the rebel-held capital, Sanaa, along with her Yemeni translator, who was released shortly afterward. There was no word until now on her fate.
The Houthis control the capital, but Yemen is also home to a powerful local al-Qaida affiliate that has carried out attacks in Sanaa and which has abducted foreigners in the past to trade for ransom or imprisoned militants.
In the video, Prime appeared sitting in the desert dressed in a black robe and looking frail and anguished. She addressed French President Francois Hollande and Yemeni President Abed Rabbo Mansour Hadi by name, saying, "Please bring me to France fast because I am really, really tired."
French Foreign Ministry spokesman Romain Nadal said his government has verified the authenticity of the video and that it was filmed in April. Nadal said officials from the ministry will meet with the Prime family on Tuesday.
He told AP that the French government is "mobilized to obtain the release" of Prime.
Word of four abducted Americans first surfaced on Friday when The Washington Post reported that three held private sector jobs, and that the fourth holds dual U.S.-Yemeni citizenship. It said the Americans are believed to be imprisoned in Sanaa. A day later, the State Department said it was working to win the release of several Americans detained in Yemen.
Another American, Sharif Mobley, has been held in unclear circumstances for more than five years. Terrorism charges against him were dropped by a court during the rule of President Ali Abdullah Saleh, who stepped down in the face of massive protests in 2012. But Mobley was never released, and was accused of killing a prison guard during an escape attempt. He is now believed to be in the custody of the Houthis, who are allied with Saleh.
The Post report said the four most recently detained are among dozens of Americans who were unable to leave Yemen or who chose to remain in the country after the U.S. closed its embassy following the Houthis' capture of the capital.
The Saudi-led coalition launched its air campaign on March 26 in a bid to roll back the rebels and restore to power President Abed Rabbo Mansour Hadi, who fled to Saudi Arabia that month in the face of a rebel advance on the south. But two months of bombing have done little to push back the Houthis and allied military units loyal to Saleh.
The airstrikes and ground fighting have killed more than 1,000 civilians and displaced a half million people, according to the U.N.
On Monday, coalition warplanes bombed the capital, targeting weapons depots in nearby Noqoum mountain. An Associated Press video showed heavy smoke rising from the mountain as explosions rocked the area.
The ongoing fighting forced a ship carrying food aid to change course. The ship, chartered by the United Nations World Food Program, was destined for the Yemeni port of Aden, but port authorities warned it to change direction because of the fighting and head to the western Red Sea port city of Hodeida, a statement from the group said.