MANILA (BLOOMBERG) - The United States will remain the Philippines' only military ally, Foreign Affairs Secretary Teodoro Locsin said, amid an increased Chinese presence near a disputed island in the South China Sea.

The US is "the only world power that is a bastion of democracy and human rights, is and will remain our only military ally. We don't need any other", he tweeted on Sunday (April 7).

Relations are improving between the US and the Philippines, which shifted towards China after President Rodrigo Duterte took power.

More than 7,000 soldiers from the Philippines and the US are participating in this year's annual joint military drills, which are taking place despite Mr Duterte's 2016 call for a split with Washington.

The Philippine leader has questioned whether the US would defend his country if China seized disputed reefs and shoals in the sea.

US Secretary of State Michael Pompeo assured in March that a defence treaty would apply if Philippine vessels or planes are attacked in the waters.

Mr Locsin's comments were made in response to a Twitter user's suggestion that the Philippines ignore the International Criminal Court (ICC) after the US moved to revoke the travel visa of prosecutor Fatou Bensouda.

They came days after Mr Duterte - in a rare rebuke to China - warned that if it did not "lay off" the Philippine-occupied Thitu Island, where more than 200 Chinese ships have been spotted in recent months, he would order his soldiers to defend it with "suicide missions".

Mr Locsin also tweeted that he "would not regret" climate change and rising sea levels if it covered the waters' disputed reefs and "exposes the foolishness of taking and weaponising them".