Screen grab from a document the Philippines submitted to UN The bathymetric model of the Benham Rise Region.

BEIJING - China on Friday dismissed concerns expressed by the Philippine defense chief over what he believed to be survey missions by its ships deep into the southeast Asian nation's 200 nautical mile exclusive economic zone (EEZ).

China's Foreign Ministry spokesman, Geng Shuang, said its ships had every right of freedom of navigation in those waters, and its research ships did pass through seas northeast of Luzon Island last year.

"But this is purely carrying out normal freedom of navigation and right of innocent passage, and there were no so-called other activities or operations," he told a regular news briefing.

"Comments from individuals in the Philippines on this do not accord with the facts."

Lorenzana on Thursday said Chinese ships were monitored in recent months at locations near the Philippines, with a warship spotted 70 miles off its western coast in the South China Sea and survey ships seen to the north and south of its eastern seaboard.

He said satellite imagery provided by allies had tracked Chinese vessels for three months last year in Benham Rise, a vast area the United Nations has declared to be part of the Philippines' continental shelf.

To the northeast of Luzon is the Western Pacific, where China is increasingly carrying out military drills.

Amid a warming relationship, President Rodrigo Duterte has frequently praised China, but Defense Secretary Delfin Lorenzana has remained openly suspicious, saying it has continued its fortification of man-made islands inside the Philippine EEZ.

China claims most of the energy-rich South China Sea through which about $5 trillion in ship-borne trade passes every year. Neighbors Brunei, Malaysia, the Philippines, Taiwan and Vietnam also have claims.