New Japanese Prime Minister Sanae Takaichi on Sunday held a series of in-person summit talks, making her overseas debut as leader by attending ASEAN-related meetings amid mounting concerns over China's maritime assertiveness in the region.

The leaders of Japan and the Philippines agreed to bolster security cooperation to help maintain peace and stability in the Asia-Pacific region, as Manila remains engaged in confrontations in the South China Sea.

Takaichi, who became Japan's first female prime minister just days ago, and Philippine President Ferdinand Marcos Jr. held talks on the sidelines of Association of Southeast Asian Nations-related summit meetings that began Sunday in Kuala Lumpur.

She said her government will work to deepen ties with the strategically important partner to realize a free and open Indo-Pacific, a vision championed by the late Prime Minister Shinzo Abe, according to the Japanese Foreign Ministry.

The Japan-Philippines Reciprocal Access Agreement, which facilitates visits by their forces for joint exercises and disaster relief operations, took effect in September.

Takaichi, known as a pro-Taiwan lawmaker with a hard-line stance toward China, also expressed her intention to help strengthen the Philippine economy and infrastructure while contributing to its food security by providing equipment for post-harvest rice processing.

Marcos thanked Japan for its official development assistance and called for deeper cooperation in various areas.

The two countries will mark the 70th anniversary of the normalization of diplomatic relations next year, when the Philippines will serve as the ASEAN chair.

Later Sunday, Takaichi held meetings with her Malaysian counterpart Anwar Ibrahim and Australian counterpart Anthony Albanese, as China continues to assert sovereignty over almost the entire South China Sea, which connects to the Pacific.

Takaichi touched on security issues in all three of her bilateral meetings in Kuala Lumpur. After the talks, she told reporters she conveyed"serious concerns" to ASEAN leaders, apparently with China in mind.

Her attendance at to the ASEAN meetings reflected her view that Southeast Asia is a crucial region for Japan's security and economy, foreign affairs experts said.