Two South Koreans and 15 Russians have been held in North Korea for a week after their boat drifted into North Korean waters, Seoul officials said Wednesday.
The crew members were aboard a Russia-flagged fishing boat when it was detained by North Korea on July 17, the Unification Ministry said in a statement.
North Korea hasn't responded to South Korea's repeated calls for the repatriation of the two South Koreans, both men in their 50s and 60s, according to the ministry.
The ministry statement said it will try to secure the freedom of the South Koreans through a close coordination with Russian authorities and communication with Pyongyang.
It said the South Koreans are currently safe but didn't provide further details.
The news came as Seoul and Moscow are squabbling over a South Korean announcement that a Russian military plane violated its airspace on Tuesday, prompting South Korean fighter jets to fire hundreds of warning shots. Russia has denied it violated South Korea's airspace.
North Korea is holding six other South Koreans it has detained in recent years for alleged attempts to build underground Christian churches inside the North and other anti-state charges, according to the Unification Ministry.
Last year, North Korea released three Americans in a goodwill gesture weeks before leader Kim Jong Un met President Donald Trump for their first summit in Singapore.
Ties between the Koreas improved last year after North Korea entered into talks on its nuclear program. South Korea's liberal president, Moon Jae-in, met Kim three times last year and facilitated negotiations between Pyongyang and Washington, including the Kim-Trump summit in Singapore.
But North Korea has recently reduced its exchanges with South Korea and requested it to stop mediating between Pyongyang and Washington amid a lack of progress in the U.S.-North Korean nuclear diplomacy. The second Kim-Trump summit in Vietnam in February collapsed without reaching any agreement due to disputes over U.S.-led sanctions on North Korea.
In yet another sign of cooling ties between the Koreas, Pyongyang is refusing to accept Seoul's offer to send 50,000 tons of rice through an international agency to protest planned U.S.-South Korean military drills, the Unification Ministry said Wednesday.
North Korea views military training between the U.S. and South Korea as an invasion rehearsal. North Korea recently suggested it may resume provocative nuclear and missile tests if Seoul and Washington go ahead with the summertime drills.