China's Foreign Ministry expressed "serious concerns" on Wednesday over the sinking of a Chinese fishing vessel by the Argentine coast guard and demanded Argentina to thoroughly investigate the incident.

In a news release on the ministry's website, spokesman Lu Kang said the Chinese vessel, Lu Yan Yuan Yu 010, which was operating in Argentine waters on Monday, was chased by the coast guard "for several hours" before it was fired upon. Shots reportedly "caused a leak in the hull and led to its sinking", Lu said.

There were no reports of casualties, and four Chinese crew members were rescued by the Argentines, while 28 others were rescued by Chinese fishing boats nearby, Lu said.

He said the State Council attaches high importance to the incident and "made important instructions".

Both the Foreign Ministry and the Chinese embassy in Argentina lodged urgent representations with the Argentine government "expressing serious concerns and demanding that the Argentine side conduct a thorough investigation", Lu said.

The ministry also demanded that Argentina inform China of the details, ensure the safety and rights of the Chinese crew and "take effective measures to avoid any repetition of such an incident", he said.

Reuters reported that the Argentine coast guard detected the vessel fishing off the coast of Puerto Madryn, Chubut province. It quoted the coast guard as saying the vessel was fishing illegally and "performed maneuvers designed to force a collision with the coast guard" before the coast guard personnel were ordered to open fire.

Xu Yicong, former Chinese ambassador to Argentina, said the decision to shoot the boat was "not careful enough" and Argentina should offer a clear explanation.

He said that China's cooperation with Argentina in the fishing goes back many years, and the two countries should "strengthen communication and coordination" to solve the problem if cases of illegal fishing arise.

The incident is "unlikely" to affect bilateral cooperation in the long term, he said.

Chen Yuanting, a researcher of Latin American studies at the Chinese Academy of Social Sciences, said such an incident is "rare" in the history of the countries' relationship.

Argentina is known for its rich fishery resources such as squid.

Chen said Argentina is friendly to China, but the incident may hint that a "delicate adjustment" of its policies toward China was made after the new Argentine government took office late last year.

Argentina is a major destination for Chinese investment in Latin America, and China should pay attention to protecting its interests in the country, she said.