MANILA -- The Philippines has deployed a fresh batch of marines and supplies to a shoal in the disputed South China Sea where a Chinese warship and surveillance vessels appeared last month and triggered a new standoff in the strategic waters, security officials said Wednesday.

The new contingent of Filipino marines replaced troops at the Second Thomas Shoal, where the arrival last month of Chinese ships sparked diplomatic protests by the Philippines.

Defense Secretary Voltaire Gazmin said the shoal lies within the Philippines' internationally recognized 200-nautical mile (370-kilometer) exclusive economic zone. China claims almost the entire South China Sea as its own and last year took control of another shoal in the Philippines' economic zone, prompting Manila to seek UN arbitration.

The Filipino marines at the Second Thomas, known in the Philippines as Ayungin Shoal, have been stationed in a decrepit military hospital ship that ran aground in 1999 on the shallow coral outcrop and has since become an awkward symbol of Philippine sovereignty.

Gazmin said he had discussed the new Philippine deployment with Chinese Ambassador Ma Keqing. Ma raised concerns that the Philippines was planning to erect concrete structures at the shoal to reinforce its territorial claim, but Gazmin said he had assured her there was no such plan.

Gazmin said he discussed the issue with Ma to prevent a possible confrontation between Chinese and Filipino forces, but stressed that the Philippines was free to undertake any activity in the shoal without notifying China.

"It's ours," Gazmin said by telephone.

Military chief of staff General Emmanuel Bautista said at least two Chinese government ships in the vicinity of the shoal did not interfere when a Philippine vessel transported the troops and food and other supplies to Second Thomas Shoal.

"We don't have any problem as long as (they're) non-confrontational and there's no hampering of our movements," Bautista told reporters. "We're there to show our flag in our territories and we will continue to do that."

Gazmin said he discussed the tense situation at the shoal with visiting US security officials, including Secretary of the Navy Ray Mabus, at a Manila meeting Tuesday.

"They're really concerned and want to be sure that this will be resolved without use of force," Gazmin said.

The Second Thomas Shoal lies near the Spratlys, a chain of resource-rich islands, islets and reefs contested by China along with Brunei, Malaysia, the Philippines, Taiwan and Vietnam. China and the Philippines figured in a monthslong standoff over another territory, Scarborough Shoal, which lies north of the Spratlys, in April last year. Philippine ships later backed off from Scarborough, giving China effective control of the shoal.

China published a new map in January that included for the first time more than 130 islands and islets in the vast waters that were not featured in its previous maps. (AP)