North Korean maritime patrol on Sunday seized two South Korean fishing boats in the East Sea near the North's border with Russia.

Maritime authorities in Sokcho in the South's Gangwon Province said the two squid fishing vessels with nine crew were captured between 2 a.m. and 4 a.m. while fishing in waters off Songjin in the North's Hamgyong Province.

Police said they believe the vessels could have strayed into the North's waters in pursuit of squid or miscalculated their course, and are investigating why the boats were captured.

The 29-ton Shinyeong and the 23-ton Gwangyeong on Friday had left the port of Geojin in Gangwon Province.