The United States said Friday that it was not seeking a permanent base in the Philippines as the allies expand military cooperation at a time of tension with China.

"I want to make a point very clear that the United States is not seeking to create or to reopen any military bases in the Philippines," State Department spokeswoman Marie Harf told reporters.

The United States and the Philippines have been working on a new pact to boost security ties ahead of President Barack Obama's October 11-12 visit to Manila.

Harf said that the United States was talking with the Philippines about how "to promote security and stability for our nation and in the region."

President Benigno Aquino has called for greater military cooperation with the United States as the Philippines, Vietnam and Japan accuse China of increasing assertiveness in staking claims in contested waters.

But reopening bases would likely also trigger resentment in some quarters of the Philippines, a former US colony.

The United States ended its permanent military presence at two bases in the Philippines in 1992 in the face of protests.

Obama has put a growing focus on Asia, with plans to shift the majority of the US Navy to the Pacific by 2020.

But US military strategists have soured on opening permanent bases, which can prove costly both financially and politically.

The United States plans to move more than 2,500 Marines to the northern Australian city of Darwin by 2016-17, but through rotations.

Nearly 80,000 US troops are stationed in Japan and South Korea on bases in a military presence that dates more than 60 years and has often been the source of discord.