MANILA, Philippines >> The Philippines has summoned a Chinese diplomat to protest new construction activities on a reef claimed by Manila in the disputed South China Sea, officials said Wednesday.

Territorial spats in the Spratly Islands involving China and several Southeast Asian nations have recently intensified, heightening tension at a time when China’s neighbors have expressed concern over its rapid military buildup.

The Philippine military has reported that a Chinese surveillance vessel and navy ships were seen unloading building materials and erecting posts in the vicinity of Iroquois Reef and Amy Douglas Bank — an uninhabited undersea hill claimed by the Philippines about 125 miles (230 kilometers) from southwestern Palawan province.

It is part of the Spratlys but well within the Philippines’ 200-mile exclusive economic zone, the Philippine Foreign Affairs Department said.

Foreign Secretary Alberto del Rosario said any new construction by China in the area "is a clear violation" of a 2002 accord that China signed with the Association of Southeast Asian Nations, which includes the Philippines. It calls for countries to exercise restraint in the disputed waters.

Chinese Charge d’Affaires Bai Tian was summoned Tuesday for talks in which Philippine officials conveyed "serious concerns" over China’s recent actions and sought clarification of them, the Foreign Affairs Department said in a statement.

Chinese Embassy officials did not immediately return calls seeking comment but China has consistently claimed sovereignty over the entire South China Sea.

Defense Secretary Voltaire Gazmin told reporters Wednesday that the Philippine military is ready to defend the country but "we’re not in the position to confront China that is a rising power in Asia."

In March, the Philippines accused two Chinese patrol boats of harassing a Philippine oil exploration ship near Palawan. Last month, the Philippine air force reported that two unidentified foreign fighter jets had flown near a Spratly island occupied by Filipino troops but China denied sending the aircraft.

Chinese media have reported that Beijing plans to install an advanced oil rig in the South China Sea in July. The Philippines expressed concern and asked China’s embassy last week about the exact location of the planned oil rig and pointed out that it should not be placed in Philippine waters.