North Korea has captured a South Korean fishing boat with seven crew members in the Sea of Japan, the South Korean coast guard said Sunday, dpa reported.
The fishermen had probably been arrested as they sailed near North Korea's exclusive economic zone, which extends 200 nautical miles from its coast, the coast guard said. It is investigating the possibility further.
The crew, four South Koreans and three Chinese nationals had been interrogated.
Seoul called on its northern neighbour to release the fishermen and their boat in accordance with international law and custom.
It was unclear whether the men were being accused of fishing illegally.
The crew had sent a satellite message in the afternoon that their boat was being towed to Songjin harbour in North Korea, the coast guard said, according to South Korean news agency Yonhap.
The 41-ton Daesung had previously been sailing in a joint fishing zone off the east coast of the Korean peninsula.
Tensions between the two states have increased since South Korea blamed its northern neighbour for the sinking of one of its warships in March, in which 46 sailors were killed.
South Korea is currently holding naval exercises off its west coast and also held joint military exercises with the US in July in order to demonstrate its military strength.
Prior to the exercises North Korea had threatened to wage a "holy war of retribution."
Last year North Korea released the crew of a South Korean fishing boat it had captured in its waters after a month. It said its territorial waters had been infringed upon.
South Korea said the boat had probably entered the North's waters due to fault in its navigational system.