File photo shows Chinese fishing boats captured by South Korean coast guard are seen at a port in Incheon, South Korea, October 10, 2016. [Photo/Agencies]

SEOUL - A Chinese fishing boat sank in west waters off South Korea on Tuesday afternoon, with seven people rescued but one still missing, South Korea's coast guard said.

The maritime police was quoted by Yonhap news agency as saying that Chinese maritime authorities informed the South Korean coast guard of the sinking of one fishing vessel among two boats fishing near the South Korean waters.

The 81-ton Chinese vessel was sailing in waters about 167 km southwest of an island off Gusan city in North Jeolla province, but it sank at about 2:20 pm local time (0520 GMT).

One Chinese sailor remains unaccounted for, but seven others were rescued.

The sinking is believed to have been caused by bad weather conditions. High seas watch is issued near the site, with waves over 4 meters high and wind blowing at a speed of 18-20 meters per second.

The Gusan coast guard dispatched a 3,000-ton patrol ship to the site right after receiving the notification. If weather conditions get better, it reportedly plans to send a helicopter for search operation.