BEIJING: China has begun combat-ready patrols in the waters around a disputed group of islands in the South China Sea, the Defence Ministry said on Thursday, and the latest escalation in tensions over the potentially resource-rich area.

Asked about what China would do in response to Vietnamese air patrols over the Spratly Islands, the ministry's spokesman Geng Yansheng said Beijing would “resolutely oppose any militarily provocative behavior”.

“In order to protect national sovereignty and our security and development interests, the Chinese military has already set up a normal, combat-ready patrol system in seas under our control,” he said.

“The Chinese military's resolve and will to defend territorial sovereignty and protect our maritime rights and interests is firm and unshakeable,” Geng added, according to a transcript posted on the ministry's website (www.mod.gov.cn).

He did not elaborate. The ministry forbids foreign reporters to attend its monthly briefings.

China is involved in a long-running dispute with Vietnam and the Philippines about ownership of the South China Sea and its myriad, mostly uninhabited, islands and atolls. Taiwan, Malaysia and Brunei also have claims.

Last week China said it “vehemently opposed” a Vietnamese law asserting sovereignty over the Paracel and Spratly Islands, which straddle key shipping lanes thought to contain rich energy reserves.

That row came days after an easing in a months-long stand-off between China and the Philippines, but shows the persistent cycle of territorial frictions triggered by what some see as Beijing's growing assertiveness in the area.

The South China Sea is potentially the biggest flashpoint for confrontation in Asia, and tensions have risen since the United States adopted a policy last year to reinforce its influence in the region.