The United States and its allies, including Japan, have been building up their militaries to counter what they see as a growing threat from China in areas such as the busy waterway of the South China Sea and around Taiwan.

At this week's summit in Washington, the three leaders discussed China's aggressive actions in the disputed South China Sea, besides unveiling a wide range of pacts to boost security and economic ties.

"We strongly deplore and strongly oppose the remarks," a foreign ministry spokesperson, Mao Ning, told a regular press briefing in response to Japanese Prime Minister Fumio Kishida's speech to U.S. Congress in which he named China the biggest challenge the world.

China strongly opposes these countries' small-group politics and any acts that instigate and drive up tension, she said about the summit.

"China opposes forming exclusive circles in the region," Mao said.

A ministry official, Liu Jinsong, met a Japanese embassy official, Akira Yokochi, to make "solemn representations" about the negative comments, the ministry said in a statement, voicing China's serious concern and strong dissatisfaction.

Liu also made "solemn representations" to the Philippine ambassador to China Jaime FlorCruz, who was summoned by the ministry over the Southeast Asian country's "negative words and deeds" related to China during the summit.

U.S. President Joe Biden and Kishida had laid out a series of projects, from codeveloping missiles to manned moon landings, while condemning China's escalatory behavior in the South China Sea region.

The two also announced plans to upgrade their military alliance, including the U.S. military command in Japan and more joint development of defence equipment.

In a separate summit with Philippine President Ferdinand Marcos Jr., Biden warned of Beijing's South China Sea moves.

(Reporting by Liz Lee; Writing by Bernard Orr; Editing by Clarence Fernandez)