The aircraft carrier strike group, which includes a trio of destroyers, joined the Philippine Navy on Friday for drills in the disputed waterway that Manila said were aimed at enhancing "interoperability, communication, and defense capabilities".

The visit to Subic Bay north of Manila comes as the Philippines looks to strengthen relations with like-minded countries in the face of increasingly tense confrontations with China over reefs and waters in the sea.

"Knowing the rise of tensions, it's even more important to uphold international law and the freedom of navigation, be it at sea or in the air," Ambassador Marie Fontanel said on the deck of the carrier.

She added that France stood with countries, like the Philippines, that shared those values.

France, which has nearly 2 million citizens in its Pacific territories, has been seeking to reassert its importance in the region, where China and the United States are battling for influence.

The French Navy's months-long operation Clemenceau 25, which included exercises with the United States and Japan in the Philippine Sea last week, was aimed at projecting power "in strategic zones where regional tensions are growing and the law of the sea is challenged by force", it said in a statement.

France is one of a handful of European countries that regularly conduct freedom of navigation patrols in the South China Sea.

China claims most of the sea including waters close to the shores of the Philippines and several other neighbours, ignoring an international tribunal ruling that its claims are without legal basis.

The Philippines and France have also been discussing a visiting forces agreement that would allow them to deploy troops on each other's territory.

Manila already has similar pacts with the United States and Australia. Japan is expected to ratify its own visiting forces deal soon, while Canada and New Zealand are also in negotiations to join that group.

The Philippines said in November that its coast guard would acquire 40 fast patrol craft from France, with plans to deploy some of them in disputed areas of the South China Sea.

Philippine Coast Guard Commandant Admiral Ronnie Gil Gavan at the time called the deal the "largest so far single purchase" in Manila's ongoing effort to modernise its coast guard, with deliveries set to start in four years.

The 25.8 billion pesos (about $440 million) deal is to be funded by development aid from the French government.