Beijing said on Monday that moves by its coast guard against Philippine vessels in the South China Sea were "professional" and "restrained", adding it had "lodged stern representations" with Manila.

Foreign Ministry spokesperson Mao Ning said the nation’s coast guard "took necessary measures against the Philippine ships in accordance with domestic and international law".

"The operations were professional, restrained, reasonable and legal," she said.

The Foreign Ministry, Mao added, "has lodged stern representations with the Philippines and expresses its strong protest".

The Philippines said on Monday it had summoned China's envoy and flagged the possibility of expelling him following the most tense confrontations between the countries' vessels in years at flashpoint reefs in the South China Sea. (AFP)