The Philippines on Monday called on nations with overlapping claims in the South China Sea to halt all action that could provoke tensions in the area, amid fears of China's expansionism.

Foreign Secretary Albert del Rosario said he backed a US proposal for a fresh regional dialogue that could take place within the year where he hoped to put the moratorium plan formally on the table.

"Let's call for a moratorium in terms of activities that escalate tension," del Rosario told ANC Television, calling on the international community "to say that we need to manage the tensions in the South China Sea before it gets out of hand."

He said he hoped to have the "reasonable proposition" taken up by the 10-nation Association of Southeast Asian Nations (ASEAN) while it continues to work with China for a binding "code of conduct" that would govern the region.

The idea for a "voluntary freeze" on possible provocation was first voiced by US Assistant Secretary of State for East Asia Daniel Russel during a visit to Myanmar, during which he noted a surge in tensions.

Russel however said the idea was not a formal proposal but merely a suggestion.

He accused China of rushing construction on reefs to "change the facts" on the ground before a United Nations arbitral tribunal rules on a case filed by the Philippines asking it to nullify Beijing's claims.

China claims nearly all of the South China Sea, including waters close to the shores of the its neighbours. ASEAN members the Philippines, Vietnam, Malaysia and Brunei, as well as Taiwan also have competing claims to the sea.

"They're accelerating their expansion agenda for the following reasons. One is they want to do this before the conclusion of the code of conduct. They're also trying to do this very quickly in anticipation of the handing down of the tribunal award," del Rosario said.

But he said the Chinese effort would be futile.

"If you take a reef and convert it to an island to be able to increase its maritime entitlements, that is not allowed," he said.

The Philippines has protested what China describes as reclamations in reefs within its exclusive economic zone, including in one it fears Beijing intends to convert into an airstrip.

China had also recently deployed an oil rig to an area close to Vietnam's coast, and sank a Vietnamese fishing boat near the area.

Chinese Foreign Ministry spokeswoman Hua Chunying rejected del Rosario's accusation of expansionism, noting that the Philippines also had installations in the area.

"This is totally unreasonable. We will by no means accept the so-called representations by the Philippines side and we require (it) to refrain from taking any action that may complicate the situation," Hua said.