Seven North Koreans cross sea border to South

SEOUL (Reuters) - Seven North Koreans crossed into the South by taking a seldom used sea route that has been the site of deadly naval clashes between the rival Koreas in the past, officials said on Tuesday.

News of the crossing came a day after the North threatened to turn the contested Yellow Sea border off the west coast of the peninsula into a firing range, raising tension as it also appears to be ending its boycott of stalled nuclear disarmament talks.

Government officials initially said the seven were seeking to defect to the South. But after questioning, group members said they wanted to return to the North, Yonhap news agency reported.

South Korea has in the past returned home North Koreans who said they accidentally drifted across the border.

Navies from the Koreas last month exchanged gunfire for the first time in about seven years near the disputed sea border, resulting in a South Korean ship being pockmarked with bullet holes and a North Korean vessel limping back to port in flames.

The two Koreas have fought two deadly naval battles in the past decade near the border, which is home to abundant fish stocks.

The North often unleashes threats while making conciliatory moves in international negotiations in order to increase its bargaining leverage by warning of the damage it could unleash in the North Asia region, which is responsible for one-sixth of the global economy, analysts said.

In a move aimed at decreasing tension, South Korea will soon complete the construction of a fiber optic cable across the border that will be used as a military hotline, a Defense Ministry official told reporters.

More than 16,000 North Koreans have defected to the South since the end of the 1950-53 Korean War, almost all of them in the past 10 years, according to the South's Unification Ministry.

The vast majority escape across the border into China, and often with the help of brokers or relief groups, seek passage to South via a third country. Once in the South, they are usually granted citizenship and given money for resettlement.

The two Koreas are technically still at war and position more than 1 million troops near their border.

(Reporting by Jon Herskovitz and Christine Kim; Editing by Jonathan Hopfner and Sanjeev Miglani)