The Democratic People's Republic of Korea (DPRK) has not responded to South Korea's request to release a South Korean fishing boat held there, the South Korean government said Monday.

The 41-ton fishing boat, which carried four South Korean and three Chinese sailors, was detained by DPRK authorities in waters presumably within the DPRK's exclusive economic zone (EEZ) off the east coast.

"There's been no notification from the DPRK side regarding the incident. Our side has not taken new moves either" other than urging the DPRK authorities to set the crew members free in accordance with the international law and practice, Seoul's Unification Ministry spokesman Chun Hae-sung told reporters in a briefing.

Seoul is still trying to figure out where and when exactly the squid fishing boat was seized, Chun added.

The incident comes as Seoul is proceeding with massive naval exercises in waters west of the divided Korean peninsula, upsetting Pyongyang, its wartime rival.