Chinese Foreign Minister Wang Yi warned the Philippines to address through dialogue what China sees as "serious difficulties" in their relations over the South China Sea, where incidents between vessels from the two sides have escalated.

Philippines resupply mission in the South China Sea.

Beijing and Manila have traded sharp accusations in recent months over run-ins involving fishing boats, coastguard ships and other vessels in the South China Sea, a strategic trade corridor where the two countries have overlapping claims.

Wang told his Philippine counterpart, Foreign Affairs Secretary Enrique Manalo, in a phone call on Wednesday that if the Southeast Asian nation misjudges or colludes with "ill-intentioned" external forces in the disputed waters, China would defend its rights and respond resolutely, according to a statement by China's foreign ministry.

"China-Philippines relations are at a crossroads," the statement cited Wang as saying. "The top priority is to properly handle and control the current maritime situation."

Manalo said on Thursday he had a frank and candid exchange with Wang.

"We both noted the importance of dialogue in addressing these issues," Manalo said, according to a foreign ministry statement. It was not immediately clear who initiated the phone call.

China lays claim to most of the waters within a so-called Nine Dash Line, which is also contested by Brunei, Malaysia, Taiwan and Vietnam.

An international tribunal invalidated China's claim to 90% of the South China Sea in 2016 but Beijing does not recognise the ruling. China has built man-made islands in the disputed area in recent years and put air strips on several of them.