South Korea's navy said Friday that it rescued four North Koreans and returned three others to the North after their fishing boats drifted south of the maritime line between the two countries near the island of Baengnyeong.

Defense Ministry officials said that four men were rescued Thursday from two boats that were in danger of sinking. Three others on a third boat were given fuel and sent back north.

Authorities said the four who remained behind are being questioned. It was unclear whether they wanted to defect.

The same area in the Yellow Sea was the scene Wednesday of an artillery exchange between the two countries.