Seoul returned four fishermen from the Democratic People's Republic of Korea and their boat on Sunday after it drifted into southern waters, military authorities said, two days after Pyongyang handed back six detained citizens of its southern neighbor.

The vessel was picked up by a Republic of Korea 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 the DPRK on Sunday in an operation along the sea border, they added.

On Friday, in a move that may help relax tensions, the DPRK returned six detained ROK men across the two rivals' heavily militarized land border.

The six are undergoing questioning by security authorities. The ROK has yet to disclose their identities or the circumstances that led to their detention in the north.

The DPRK said in February 2010 that it was holding four people from the south 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 DPRK's third nuclear test in February, but then appeared to enter a rapprochement stage that saw the two rivals agree to reopen their joint industrial park in Kaesong.

But the mood quickly soured again when Pyongyang canceled a scheduled reunion last month for family members separated by the Korean War.

(China Daily 10/28/2013 page11)