* Kim Jong Un snapped photos with K-pop stars after concert
* Two Koreas are slated for summit on April 27
* Concert follows recent thaw in relations between two Koreas
* Performance coincides with start of U.S.-S.Korea military drills (Adds timing of U.S.-S.Korean military drills, details of event, N.Korean crackdown on foreign media, paragraphs 6-7, 11-12, 17-20)
SEOUL, April 1 (Reuters) - North Korean leader Kim Jong Un and his wife, Ri Sol Ju, were among the hundreds in Pyongyang on Sunday watching South Korean K-pop singers perform in the North for the first time in more than a decade as tensions between the old rivals thaw.
It was the first time a North Korean leader had attended a South Korean performance in the North's capital. Kim was seen clapping in tune to some of the songs and took photographs with the performers after the show.
"Our dear leader comrade said his heart swelled and he was moved by the sight of his people deepen their understanding of South Korean popular culture and cheer with sincerity," the North's KCNA state media said.
The North Korean audience clapped, cheered, sang along to some of the songs and later presented the South Korean performers with bouquets.
"(Kim Jong Un) showed much interest during the show and asked questions about the songs and lyrics," Culture Minister Do Jong-whan told reporters after the show.
Sunday's performance coincided with the start of annual joint South Korean-U.S. military drills, which have previously been met with denunciations and missile launches by the North, and were delayed and shortened this year in order not to overshadow the Olympic detente.
The recent thaw in relations, which could even lead to a summit between Kim and U.S. President Donald Trump in May, follows months of increased tensions after North Korea conducted missile launches and a nuclear test last year in defiance of United Nations Security Council sanctions.
Sunday's concert was held under the title "Spring is Coming" at the East Pyongyang Grand Theatre, performed by an elite lineup of South Korean artists including veteran vocalists Cho Yong-pil, Lee Sun-hee, rock star Yoon Do-hyun and singer Baek Ji-young, as well as K-pop girl band Red Velvet.
Like the concert title, the performance had brought a "spring of peace" to the two Koreas, Kim was also cited as saying by the North's central news agency, and expressed wishes for a "prosperous autumn."
The North Korean leader's face was slightly flushed in a group photograph with the performers distributed by North Korean state media. He was seen in another directly addressing members of Red Velvet, which commands more than 4.6 million followers on Instagram.
North Korean staff were spotted outside the performers' dressing rooms using Japan-made electronic devices to serve coffee and cupcakes, including Western Lavazza and Coffee-mate products, according to a South Korean media pool report.
Sunday's two-hour concert in Pyongyang, along with a separate taekwondo performance earlier in the day, came as South Korea's engagement with North Korea has grown since Kim expressed his willingness for more contact between the two countries.
Athletes from North and South Korea marched under a unified peninsula flag at the opening ceremony at the Pyeongchang Winter Olympics in February. The significant thaw in the inter-Korean relations has led them to set a date for their first summit in more than a decade on April 27.
The two Koreas are technically still at war after the 1950-1953 conflict ended with a ceasefire rather than a peace agreement.
The South Korean delegation included artists, concert staff, taekwondo demonstrators, reporters and government officials. They traveled to Pyongyang on Saturday in a reciprocal cultural visit after North Korea sent performers to the South in February, the South's Culture Ministry said.
In addition to the concert, a team of South Korean taekwondo demonstrators performed on Sunday at the Pyongyang Taekwondo Hall, drawing more than 2,300 North Koreans, including Choe Hwi, chairman of the National Sports Guidance Committee.
The images of Kim posing and laughing with the young South Korean pop stars and applauding in the stands contrasts with reports from North Korean defectors who say he has overseen a crackdown on foreign media.
"North Korean refugees overwhelmingly and consistently report that it has become more dangerous to consume foreign media under Kim Jong Un’s crackdowns," Sokeel Park, the South Korea country director for refugee aid organization Liberty in North Korea, said on Twitter.
A 2015 survey of North Korean refugees conducted by the U.S. government's Broadcasting Board of Governors found that 77 percent of respondents said it had become more dangerous to listen to foreign radio under Kim.
South Korean movies were often reported to be especially taboo compared to Chinese films, according to a report by the InterMedia consultancy group, with North Koreans potentially facing prison time if caught.
Seohyun, an actress and vocalist with South Korean girl group Girls' Generation, sang a North Korean pop song called "Blue Willow Tree." She had performed with the North's Samjiyon Orchestra in Seoul in February.
Cho Yong-pil, 68, sang a string of hits including "The Cafe in the Winter," "Short Hair" and "Let's Go on a Trip." Cho staged a solo concert in Pyongyang in 2005 - the last concert by a South Korean artist in the North before Sunday's performance.
The same South Korean singers will hold a joint concert with North Korean performers on Tuesday at the Ryukyung Chung Ju Yung Gymnasium, a joint project between the North and South named after Hyundai Group billionaire founder Chung Ju-yung, who had long advocated inter-Korean cultural and economic exchanges.
Kim had been planning to attend the Tuesday performance but decided to watch Sunday's show due to "political schedules," KCNA and South Korean officials there said. (Reporting by Heekyong Yang and Christine Kim Additional reporting by Josh Smith Editing by Louise Heavens, Peter Cooney and Paul Tait)