Philippine President Ferdinand Marcos Jr. has offered to remove a U.S. missile system from the Philippines if China halts what he called its “aggressive and coercive behavior” in the disputed South China Sea.

The Philippines said on Saturday it has suspended a scientific survey in the South China Sea after two of its fisheries vessels faced "harassment" and aggressive behaviour from China's coast guard and navy.

Philippine security officials said Thursday they took into custody five more Chinese spies, following the arrest of a compatriot for espionage this month.

The US military deployed the Typhon missile system in the northern Philippines last year as part of an annual joint exercise, and Filipino troops have been training with it, with plans to acquire the system as a means to protect Manila's maritime interests.

The Philippines will soon decide on an international platform to sue China for alleged damage to the marine environment, its justice minister said, as it pursues a second high-profile legal challenge against Beijing over the South China Sea.