Japan will loan the Philippines 64.38 billion yen ($413 million) to buy the five 97-metre Multi-Role Response Vessels and pay for the "development of the required support facilities", the foreign ministry said in a statement.

"This will support the PCG in improving its capabilities for maritime operations particularly in addressing transnational crimes," the statement said, referring to the Philippine Coast Guard.

Tokyo is a top provider of overseas development assistance to the Philippines.

The Philippine Coast Guard currently has two 97-metre patrol vessels as part of a fleet seen as inadequate for patrolling waters around the vast archipelago nation.

In recent months, its vessels have been involved in several collisions with Chinese coast guard ships around disputed reefs in the South China Sea, which Beijing claims almost entirely.

Philippine Coast Guard boats have also been fired on with water cannons by the China Coast Guard, with the latest incident happening on April 30 near the China-controlled Scarborough Shoal.

The triangular chain of reefs and rocks that make up Scarborough Shoal lies 240 kilometres (150 miles) west of the Philippines' main island of Luzon and nearly 900 kilometres from Hainan, the nearest major Chinese land mass.

Japan invaded and occupied the Philippines during World War II, but the two countries have since grown closer due to trade and investment, and more recently, to counter China's assertiveness in the region.

As part of efforts to deepen their security cooperation, Manila and Tokyo are negotiating a defence pact that would allow the countries to deploy troops on each other's territory.

Leaders of Japan and the Philippines -- both longtime allies of the United States -- were in Washington last month for a trilateral summit with US President Joe Biden.

Tensions over the South China Sea, combined with saber rattling over China's claims to the self-governing island of Taiwan, have prompted Biden to boost alliances in the region.

Beijing claims most of the waterway, brushing off rival claims from other countries, including the Philippines, and an international ruling that its assertion has no legal basis.