A ship carrying the North Koreans was found drifting near Ulleung Island in waters off South Korea's east coast on June 23 suffering from an engine breakdown.

"As repair of the ship is likely to be completed today, we will be able to repatriate them to the North around Thursday," said a ministry official.

South Korea has rescued North Korean ships going astray on five occasions so far this year. Thirteen fishermen were sent back home and two chose to defect to South Korea, the ministry said.

"As North Korea has recently stressed a need to boost fishing, small North Korean boats may have sailed farther, causing accidents (such as engine breakdowns)," the official said.

South Korea has sent back fishermen who drifted into its waters in the past after making certain they did not wish to defect.

South and North Korea are technically still at war after the 1950-53 Korean War ended in a truce, not a peace treaty. (Yonhap)