China’s newspaper People's Daily said on Tuesday that recent construction work by Philippine troops on an island claimed by Manila violates the spirit of a preliminary agreement reached last month to resolve disputes in the East Sea.

That shows Manila had merely been putting on "a little show," the paper said in a signed editorial. China won't sit idly by while its territory is swallowed up by others, it said. China claims the East Sea and all its islands as its territory.

"Were there to be a serious strategic miscalculation on this matter, the due consequences would have to be paid," the newspaper said.

Philippine Foreign Secretary Albert del Rosario did not directly address the new Chinese accusation but said Manila was committed to a "rules-based regime and to a peaceful resolution" of the disputes.

"We maintain that what is ours is ours and are prepared to validate our position in accordance with international law, specifically UNCLOS," del Rosario said, referring to the United Nations Convention on the Law of the Sea.

"We invite China to do the same," he said in a brief statement.

AP