TOKYO (Updated) — 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," and praised Tokyo for demonstrating solidarity with the Philippines in advocating the problem.

"We reiterate, we ask China: Is this a necessary step? And if stability is a necessary prerequisite to prosperity for all, and if prosperity for all our peoples is the be-all and end-all of any government, then perhaps they should re-examine all of these efforts and see whether or not this is necessary given the increasing tensions that are happening because of these activities," he said.

The President also raised concern that China might bring people to live on the artificial islands that it constructed in the South China Sea.

"You have previously features that could not support life. Now, they are being turned into islands. It is not far-fetched to imagine that at some point in time there may be people, and we are, of course, bothered by comments; for instance, the last ambassador of the Philippines was asked: Do you intend to declare an ADIZ (Air Defense Identification Zone) over the Spratlys and over the South China Sea? And they said that they are empowered to do so," he said.

"This reclamation effort seems to go against both the letter of this agreement entered into, as well as the spirit of the law," he said, referring to the Declaration of Conduct of Parties in South China Sea and the United Nations Convention on the Law of the Seas (Unclos).

China has been claiming almost the entire South China Sea even those within the 200 nautical miles exclusive economic zone of other countries like the Philippines.

Aquino also said that he was thankful that other countries, such as the United States, Japan and the European Union, have raised their concern over China's activities in the disputed area.

"When America and Japan both talked about their concerns, and this voice is also seconded by the European Union and various other countries that have expressed concern about the reclamation efforts, that reminds China, I believe, of its responsibility as a member of the community of nations to adhere to international law and to perhaps re-examine its objectives relative to its maintaining the goodwill of the rest of the world," he said.

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 Japanese 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.

Since both countries are U.S. allies and share concerns over China's maritime activity, the Philippines is extremely important to Japan, said Kenko Sone, spokesman at Japan's Prime Minister's Office.

Foreign Ministry officials said Monday that Abe and Aquino were also expected to expand their defense cooperation in other areas, including the transfer of Japanese military equipment and technology to the Philippines, possibly related to maritime reconnaissance. Tokyo eased its self-imposed ban on military exports last year.

Under Abe's push to expand Japan's international defense role, Japan has been expanding its defense cooperation with a number of countries to complement its cornerstone alliance with the U.S.

Manila has protested over China's stepped-up reclamation work on Philippine-claimed islands and maneuvers against Filipino air patrols and fishermen. During an international defense conference last week in Singapore, U.S. officials said China's expanding reclamation work could be for a military use. (AP/SDR/Sunnex)