The drills followed the signing less than a month ago of an agreement between Manila and Tokyo to allow the deployment of troops on each other's territory.

The Japanese destroyer JS Sazanami and the Philippine guided missile frigate BRP Jose Rizal took part in the two countries' first bilateral "Maritime Cooperative Activity", the Philippine military said in a statement.

"This activity was part of the ongoing efforts to strengthen regional and international cooperation towards realising a free and open Indo-Pacific."

The two vessels held a communications exercise and undertook tactical manoeuvres in the West Philippine Sea, Manila's name for parts of the South China Sea that are closest to the Filipino coast.

These "enhanced the tactical capabilities of the Philippine Navy and the (Japan Maritime Self-Defence Force) and reinforced the strong ties and mutual commitment to maintaining peace and stability in the region," the statement added.

During the exercises, a Jiangdao-class corvette of the Chinese navy was observed in the area about 7.4 kilometres (4.6 miles) away and a Jiangkai-class frigate was seen about nine kilometres away, Philippine military spokesman Xerxes Trinidad said.

The Chinese warships were observed "tailing the formation" but "did not interfere" with the drills, he said in a statement.

"The exercise proceeded as planned, achieving its objectives of improving tactical capabilities and strengthening cooperation" between Philippine and Japanese navies, Trinidad added.

A similar exercise was held two days earlier, also in South China Sea waters close to the Philippines, between the Filipino navy patrol ship BRP Ramon Alcaraz and the US Navy's littoral combat ship USS Mobile.

The Philippines and Japan are longtime allies of the United States, which has been strengthening its alliances from Canberra to Tokyo to counter China's growing military might and influence in the region.

The deepening of Filipino-Japanese security ties comes as China's sabre-rattling towards Taiwan and over the South China Sea fuels fears of a potential conflict that could drag in the United States.

There have been escalating confrontations at sea between Chinese and Philippine ships as Beijing steps up efforts to push its claims to nearly all of the strategic South China Sea.