SEOUL • Five North Koreans crossed into South Korean waters in a boat, sailing across a heavily guarded maritime border between the two nations in what appeared to be an attempt to flee the North, said South Korean coast guard officials.

The North Koreans - four men and one woman - indicated that they wanted to defect to the South when their boat was stopped by a South Korean coast guard patrol ship south of the maritime border and off the eastern coast of the Korean Peninsula, the officials said.

Despite these initial indications, South Korean officials said a formal investigation was required before concluding that the North Koreans were indeed defectors.

"Investigators from relevant government agencies are currently interrogating them to determine whether the North Koreans want to defect and other details," said Mr Choi Su Jun, an officer with the coast guard in the city of Donghae on South Korea's eastern coast.

The South Korean patrol ship first found the North Korean boat on Saturday evening and guided it to the nearby port of Mukho, Mr Choi said.

North Korean fishing boats occasionally drift into South Korean waters after experiencing engine trouble or running out of fuel. South Korea returns those on board to the North unless they express a desire to defect.

This year alone, seven North Korean boats with a total of 28 people on board have been rescued by the South Korean navy or coast guard, including the one that crossed the border on Saturday and another found off the eastern coast on June 23.

Of the 28 people, 21 have chosen to return home to the North, while two have defected to South Korea. The five picked up on Saturday are still being questioned.

When North Koreans choose to stay in the South, the North has almost always accused South Korea of holding them against their will.

South Korea, for its part, has accused the North of holding hundreds of South Korean fishermen against their will after their ships strayed into North Korean waters. In some cases, according to the South, they were abducted by the North in the decades after the 1950-53 Korean War.

More than 30,000 North Koreans have fled to the South since a widespread famine hit their isolated and impoverished country in the late 1990s.

Nearly all of them travelled through China, but some have defected through the heavily guarded land or maritime borders separating the two Koreas.

Most of the defectors said they were fleeing food shortages or political persecution in the North or had developed a yearning for life in the South while watching South Korean movies and TV dramas smuggled into the North through China.

Some said they had learnt about life in the South while listening to banned radio broadcasts from the South.

NYTIMES