The Malaysian Maritime Enforcement Agency (MMEA) said only 82 foreign fishing boats were seen in Malaysia's waters in the South China Sea near Miri, Sarawak, by Friday (March 25), a day after a Cabinet minister said 100 Chinese boats were sighted in the area.

MMEA director-general Ahmad Puzi Ab Kahar also told reporters on Saturday the agency could not yet determine who the boats belonged to due to the lack of identification such as flags, or panel numbers on the boats, state news agency Bernama reported.

His update came two days after Minister in the Prime Minister's Department Shahidan Kassim was reported by Malaysia media as saying 100 Chinese fishing boats had been spotted in the waters, amid rising regional tensions in the contested waters.

Shahidan told reporters a Bombardier aircraft and three vessels from the Royal Malaysian Navy and the MMEA had been deployed to check on the "encroachment".

Ahmad Puzi said on Saturday the MMEA tried to contact the boats via 'Channel 16', the communication channel used to check the status of foreign boats entering the waters of a another country, but there was no response.

"On March 24 (Thursday), a Bombardier aircraft was directed to conduct air surveillance in the morning and evening, due to the presence of foreign fishing boats. Today, we continued to monitor the area more closely," Ahmad Puzi was quoted By Bernama as telling reporters.

"Three MMEA vessels are still stationed off the coast of Miri to monitor the foreign boats," added the official.

"Action will be taken in accordance with the laws of Malaysia against foreign fishermen who encroach into our country's waters."

China's foreign ministry spokesman, Hong Lei, said at a regular briefing on Friday that he did not "understand the details" of what the Malaysian government had said about the boats.

"What I want to point out is that now is the fishing season in the South China Sea ... At this time of year, every year, Chinese trawlers are in the relevant waters carrying out normal fishing activities," Hong was quoted by Reuters as saying. He did not elaborate.

China claims virtually all of the South China Sea, while Brunei, Malaysia, Vietnam, Taiwan and the Philippines claim parts of the waterway through which trade worth US$5 trillion (S$6.9 trillion) passes every year.

Tensions flared between China and Indonesia last week over the actions of a Chinese coast guard vessel in waters off Indonesia's Natuna islands.