MANILA - China on Monday defended its move to send a patrol ship to the disputed Spratly islands, saying it was not a violation of an agreement to maintain the peace in the South China Sea.

The vessel is a "fishery patrol ship, not a warship," Hua Ye, a spokesman for the Chinese embassy in Manila, said in a statement.

"I don't think the Chinese side has done anything or violated the Declaration of the Conduct of the Parties in the South China Sea."

That 2002 declaration called on all claimants to the Spratlys -- including the Philippines and China -- to refrain from any action that could heighten tension, including military build-up and construction work.

The statement came a day after China's Beijing News said a converted naval patrol vessel had been dispatched to what it claims are its exclusive maritime zones covering the disputed Spratlys and Paracels islands.

The report said the ship would assist Chinese fishing boats and transport vessels. However, the move is largely seen here as China flexing its military might against the smaller claimants.

Presidential spokesman Cerge Remonde said the foreign ministry in Manila was "already using normal diplomatic channels to solve this diplomatically."

"While it is true that this is a cause for concern, let us not overreact," Remonde said.

He noted however that the US government has complained that one of its research vessels was harassed recently by Chinese naval ships in waters off southern China.

The Philippines foreign ministry said it would keep to the 2002 declaration and urged other claimants to do the same.

Meanwhile, Philippine Navy spokesman Colonel Edgardo Arevalo said they were trying to verify and monitor the exact location of the Chinese vessel, but also urged the public to remain calm.

"There is yet no cause for alarm as sending patrol boats by different claimant countries in the areas where they claim in Spratlys is tolerated," Arevalo said.

He added that, like China, the Philippines has troops stationed in some islets to "protect territorial integrity."

The Spratlys, a chain of atolls and reefs, is significant because it is believed to sit atop vast mineral and oil deposits.

Apart from China and the Philippines, it is also being claimed in whole or in part by Brunei, Malaysia, Taiwan and Vietnam.