A South Korean fishing vessel that was seized by North Korea on Sunday is under investigation in the North.

The 41-ton "Daeseung" was seized in waters northeast of the South's Sokcho City on Sunday while fishing for squid.

Authorities are looking into whether the boat ventured into North Korean waters when it was seized.

In the last satellite contact with the Coast Guard around 2:35 p.m. Sunday, the Daeseung said it was being towed to Songjin Port in North Hamgyeong Province by North Korean authorities.

The South’s Coast Guard tried to contact the crew of the boat all night Sunday but to no avail.

On board the boat were four South Korean sailors, including the captain, and three Chinese in their 30s.