The Philippine president is on his sixth visit to Japan in less than five years, signaling his country's deepening ties with Tokyo amid increasing concerns by both sides about China's assertiveness in regional seas.

In a speech in Tokyo on Wednesday, President Benigno Aquino III criticized what he called China's "unlawful territorial claim."

Aquino has been accorded rare state guest status, and also was invited to speak later Wednesday to the upper house of parliament.

During his four-day visit, Aquino will hold talks with Prime Minister Shinzo Abe focusing on defense and security ties. The two leaders are expected to sign a deal confirming Japan's provision of 10 patrol vessels to the Philippine coast guard to bolster its patrolling capability around Manila-claimed South China Sea islands.