Maritime issues between the Philippines and China remain a "serious concern", a Philippine official said on Friday, as the countries pledged to use diplomacy to resolve differences peacefully during high-level talks.

The Philippines hosted this week the first in-person meeting between diplomats from the countries since before the COVID-19 pandemic, amid a flare-up in tensions over what Manila described as China's "aggressive activities" in the South China Sea.

"Both our countries' leaders agreed that maritime issues should be addressed through diplomacy and dialogue and never through coercion and intimidation," Philippine foreign ministry undersecretary Theresa Lazaro said at the opening of bilateral talks on the South China Sea.

The discussions come two months after President Ferdinand Marcos Jr's state visit to China, where President Xi Jinping said he was ready to manage maritime issues "cordially" with Manila.

"Maritime issues are an important part of China-Philippines relations that should not be ignored," China's Vice Foreign Minister Sun Weidong said.

"In the past years, through friendly dialogue and consultations, the two countries have generally managed and effectively dealt with our differences on maritime issues. And we have also advanced our practical cooperation and our mutual trust," added Sun, who is on a three-day visit to Manila.

Beijing, which claims large parts of the South China Sea, including some areas in Philippine waters, has expressed concern over an increasing U.S. military presence in its neighbour, accusing Washington of increasing regional tensions.

Last month, Marcos granted the United States expanded access to military bases, amid China's growing assertiveness in the South China Sea and towards self-ruled Taiwan.

The agreement has been seen as a sign of a rekindling of ties between Manila and its former colonial master, which soured under his predecessor, Rodrigo Duterte.

Marcos, the son of the late strongman whom Washington helped flee into exile during a 1986 "people power" uprising, has repeatedly said he could not see a future for his country without the United States.

Last month, the Philippines accused China's coast guard of using a laser against one of its vessels supporting a resupply mission for troops in the disputed Spratly islands. Marcos later summoned the Chinese ambassador to relay his concern over the intensity and frequency of China's activities in the area.

Maritime differences with Beijing were a "serious concern" but could be resolved through the "exhaustion of all diplomatic means", Lazaro said. (Reporting by Karen Lema and Neil Jerome Morales Editing by Ed Davies)