New rules outlined by China's coast guard that could result in the detention of foreigners in the West Philippine Sea should not cause any concern, a Chinese foreign ministry spokesperson said on Wednesday (May 29), after Philippines President Ferdinand Marcos Jr said the rules were an escalation and "worrisome".

China, which has maritime sovereignty disputes with the Philippines and other countries, issued new rules effective June 15 that would enforce a 2021 coast guard law and allow detention of foreigners suspected of trespassing.

The rules aim to standardize law enforcement and better uphold maritime order, Chinese foreign ministry spokesperson Mao Ning said at a regular news conference. There is no need for any individual or entity to worry "as long as there is no illegal behavior", Mao added.

The Philippines "will use any point of contact with China to stop aggressive actions" and allow Filipino fishermen to fish in the South China Sea, Marcos told reporters during a state visit to Brunei.