SEOUL, Nov. 8 (Yonhap) -- A North Korean man crossed the maritime border into South Korea on a raft late last month, the same day that 21 other North Koreans were found drifting aboard a boat off the South's west coast, a government source said Tuesday.

"One North Korean man was discovered by our Navy aboard a rubber raft around 3 a.m. on Oct. 30," the source said. "He had drifted to waters near Yeonpyeong Island (near the border in the Yellow Sea)."

The source said the man appeared to have taken off from Kaemori in Hwanghae Province, a North Korean artillery base about 13 kilometers away from Yeonpyeong. It was from Kaemori that the North launched artillery shots toward Yeonpyeong in November last year.

Also on Oct. 30, a five-ton wooden boat carrying the 21 North Koreans was spotted by South Korean Navy sailors. They have expressed their wish to defect.

Chronic food shortages and harsh political oppression in the North have forced more than 22,000 North Koreans to defect to South Korea since the 1950-53 Korean War. Most North Koreans cross the country's land border with China to reach the South, with some choosing to take the sea route.