Foreign Secretary Alan Peter Cayetano said the Philippines is open to an offer from US President Donald Trump to mediate in the long-running disputes in the South China Sea.

“We welcome that offer. Let's see how everyone responds," Cayetano told reporters at the sidelines of the Association of Southeast Asian Nations ministerial meeting before the formal start of the summit where ASEAN leaders and their counterparts from China, Japan, Korea, Australia, New Zealand, India, Russia and the US gather in Manila beginning Monday.

Cayetano said he thanks Trump, calling such a move "a very kind and generous offer because he is a good mediator."

"But of course the claimant countries have to answer as a group or individually and not one country can just give an instant reply because mediation involves all the claimants and non-claimants,” Cayetano said.

The South China Sea is one of the world's most vital sea lanes.

A news report said Trump said he is ready to mediate between ASEAN claimants in the South China Sea dispute DMS