A Chinese official on Thursday denied Vietnamese allegations that a Chinese coast guard ship sank a fishing boat in the South Chinese Sea last week.

According to the official, who spoke on condition of anonymity, China's coast guard found two Vietnamese boats fishing near Huaguang Reef of China's Xisha Islands on Saturday.

The coast guard urged the fishing boats to leave, but they turned a deaf ear, said the official. The coast guard sent a law-enforcement ship to "board, inspect and drive away" the fishing boats, said the official.

The whole process was carried out in line with the law and with a video record, the official said, adding that there was no deliberate act to sink the Vietnamese boat.

According to the official, the Vietnamese fishing ships violated China's law and so it was quite natural that China took law-enforcement measures.

China has no idea how the Vietnamese ship sunk, and China dispatched rescue ships immediately after receiving notification from Vietnam, said the official, who urged the Vietnamese government to educate the fishermen to stop fishing in China's territory.

The Vietnam Fisheries Society said in a statement on Tuesday that two Vietnamese boats were chased by a pair of Chinese coast guard ships. One ship was boarded by the Chinese coast guard who forced the crew overboard, while a second vessel was prevented from reaching the stranded fishermen.

"Chinese men jumped onto fisherman Vo Van Luu's boat, struck the Vietnamese sailors and ... sunk the vessel," the statement alleged.

Foreign Ministry spokesman Lu Kang refuted the allegation on Tuesday, saying that the Chinese coast guard offered timely help after receiving notification from its counterpart.

"China Maritime Search and Rescue Center was notified by its Vietnamese counterpart, saying that a Vietnamese fishing boat sunk 55 nautical miles to the southeast of Yongxing Island. All five fishermen on board fell into the water," Lu said.

After receiving the notification, China immediately mobilized the coast guard to assist with the rescue, he said, adding that all the fishermen have been rescued.