MANILA, Apr. 18 (Reuters) - The Philippines' decision to ramp up ties with Japan and the United States is a "sovereign choice", its foreign ministry said on Thursday, urging China to "reflect upon its own actions" in the South China Sea.

"The source of tension in our region is well known to all," the foreign affairs department said in a statement.

"It is China's excessive maritime claims and aggressive behaviour, including its militarisation of reclaimed features, that are undermining regional peace and stability and raising tensions," it added.

The statement was in response to China's criticism over the recent trilateral summit between U.S. President Joe Biden, Japanese Prime Minister Fumio Kishida and Philippine President Ferdinand Marcos Jr.

The three leaders have jointly expressed serious concerns about China's "dangerous and aggressive behaviour in the South China Sea".

Chinese foreign ministry spokesperson Mao Ning told a briefing last week Beijing opposes "forming exclusive circles in the region".

The Philippine foreign ministry said China's actions are undermining regional peace and stability and raising tensions in the disputed waterway.

China claims almost the entire South China Sea, a conduit for more than $3 trillion in annual ship commerce. Its territorial claims overlap with waters claimed by the Philippines, Vietnam, Indonesia, Malaysia and Brunei.

In 2016, the Permanent Court of Arbitration in the Hague said China's claims had no legal basis, a decision Beijing has rejected.

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