By Kim Sue-young
South Korea asked North Korea to release immediately a fishing boat which was towed to the secretive state after mistakenly crossing the Northern Limit Line (NLL) Thursday.
The North said an investigation was underway.
The 29-ton 800 Yeongan with four crewmembers on board was apprehended by a North Korean patrol boat after it strayed into North Korean waters off the east coast.
The squid catcher was presumed to have had a malfunction in its satellite navigation system, according to officials.
"The government sent a message to the North's maritime authorities via an inter-Korean communication channel, calling for the immediate release of the boat and crewmembers," unification ministry spokesman Chun Hae-sung said.
There was no immediate action, but Pyongyang acknowledged receiving the message and said it would check into the situation, according to spokeswoman Lee Jong-joo from the same ministry.
The vessel was towed to the port of Jangjon at 9:30 a.m., defense ministry spokesman Lee Bung-woo said.
After the fishing boat drifted into North Korean waters, a Navy vessel radioed the North Korean patrol for the return of the boat twice but received no response, according to military sources.
Talks for the return of the crew are likely to be more complicated due to the soured inter-Korean relations, North Korea watchers said.
"If the trespassing was due to a simple malfunction, North Korea will set the boat free after a quick investigation," professor Yang Moo-jin of the University of North Korea Studies in Seoul told The Korea Times.
"But if there were other causes, the situation could become more complicated," he said.
There are some measures agreed on between the two Koreas regarding unexpected incidents such as this, Yang said.
A South Korean fishing boat that accidentally crossed the NLL in December 2006 was sent home after being detained for 18 days.
Separately, a South Korean working in a joint industrial complex in the North Korean border city of Gaeseong has been held in the North for the past four months.
The detainee allegedly made derogatory comments about the North Korean regime and attempted to entice a female worker to defect to the South.