Japan and the Philippines said on Friday they will start negotiations for a defence agreement that would allow the countries to deploy troops on each other's territory.

Tokyo and Manila -- longtime allies of the United States -- are deepening their defence cooperation.

The accord would create the legal basis for the countries to send defence personnel to each other's territory for training and other operations.

Philippine President Ferdinand Marcos and Japanese Prime Minister Fumio Kishida announced the start of reciprocal access negotiations following talks in Manila.

"We are cognisant of the benefits of having this arrangement both to our defence and military personnel and to maintaining peace and stability in our region," Marcos said, as he stood beside Kishida in the presidential palace.

Kishida said the countries also agreed to further boost cooperation between Japan, the United States and the Philippines.

Japan would help "improve the Philippines maritime law enforcement capability including the provision of patrol vessels and defence equipment and technology cooperation," Kishida said.

Japan will provide the Philippines with a coastal radar surveillance system as part of a 600 million yen (US$4 million) security assistance package, the leaders said.

Kishida is the first Japanese prime minister to visit the Philippines since 2017.

He is scheduled to address a special joint session of Congress on Saturday -- the first Japanese leader to do so -- and visit the Philippine Coast Guard headquarters.

Japan invaded and occupied the Philippines during World War II, but the two countries have since grown closer due to trade and investment.

Tokyo has signed similar reciprocal access agreements with Britain and Australia in the past two years.

The Philippines has equivalent pacts with the United States and Australia. (AFP)