HAVANA (Reuters) -- Pope Francis and the head of the Russian Orthodox Church meet in Havana on Friday, nearly 1,000 years after Eastern Orthodoxy split with Rome, for the first encounter in history between a Roman Catholic pope and a Russian Orthodox patriarch.
The two religious leaders, guests of a Communist government, will address the millennium-long rift between the Western and Eastern branches of Christianity.
They are also expected to unite in an appeal for an end to persecution and killing of Christians in the Middle East.
The meeting will also carry political overtones, coming at a time of Russian disagreements with the West over Syria and Ukraine.
The Vatican and the Moscow Patriarchate made the surprise announcement just a week in advance of the meeting.
Patriarch Kirill arrived in Havana on Thursday with his long beard, tall domed hat, white stole and black robes. He was welcomed by Cuban President Raul Castro, dressed in a business suit rather than his usual olive green military fatigues.
Francis was due to arrive on Friday afternoon for a three-and-a-half-hour stop in Cuba on his way to a long-scheduled visit to Mexico.
Castro is an ally of Russia who received Francis in Cuba just five months ago. The Argentine pontiff previously played a role in rapprochement between the United States and Cuba, who restored diplomatic relations last year after a 54-year break.
Now the pope is seeking to repair a much longer rupture. Eastern Orthodoxy split with Rome in 1054, and today the Russian church counts some 165 million of the world's 250 million Orthodox Christians.
Kirill, on a longer stay, will also visit Cuba's small Russian Orthodox Church, built from 2004 to 2008 and attended by Russian holdovers from the decades of Soviet influence in Cuba.
Russian President Vladimir Putin has supported the Russian church, which in turn has backed Kremlin foreign policy, most notably in Ukraine and the Middle East.
Putin has also improved relations with Cuba, which were strained following the collapse of the Soviet Union in 1991.
In 2001, during Putin's first term as president, former Cuban President Fidel Castro approved construction of a Russian Orthodox church, which was given prime real estate on Havana Bay in what is now a booming tourist zone.
In 2004, when he was head of the Russian church's foreign affairs department, Kirill came to Havana to preside over a ceremony laying the first stone.