SEOUL - Seoul returned four North Korean fishermen and their boat Sunday after it drifted into southern waters, military authorities said, two days after Pyongyang handed back six detained South Koreans.
The vessel was picked up by a South Korean navy ship on Saturday after being spotted stranded off the country's east coast following engine failure, officials said.
The fishermen and their boat were handed over to North Korea Sunday in an operation along the sea border, they added.
On Friday, in a move that may help relax tensions, North Korea returned six detained South Korean men across the two rivals' heavily-militarised land border.
Border crossings between North and South are extremely rare and it is most likely that the six people returned on Friday had entered North Korea from China.
The six are under questioning by security authorities. South Korea has yet to disclose their identities and the circumstances that led to their detention in the North.
North Korea said in February 2010 that it was holding four South Koreans who had "illegally entered" the country -- and it is presumed that they are among the six returnees.
The surprise return on Friday would appear to be a conciliatory gesture at a time when North-South ties have been blowing hot and cold.
Tensions soared for months after the North's third nuclear test in February, but then appeared to enter a rapprochement stage that saw the two rivals agree to re-open their joint industrial park in Kaesong.
But the mood quickly soured again when Pyongyang cancelled a scheduled reunion last month for family members separated by the Korean War.