China has expressed its opposition to Vietnam’s exploitation of oil and gas resources in the South China Sea, while rejecting recent accusations from Hanoi that Beijing had violated the Southeast Asian country’s sovereignty.

The spat appears to have indicated the wariness of its regional counterparts over Beijing’s rising clout and the increasingly complicated situation in the South China Sea after the US made a statement aimed at reasserting its influence in Asia last year.

“China’s stance on the South China Sea is clear and consistent. We oppose the oil and gas operations conducted by Vietnam, which have undermined China’s interests and jurisdictional rights in the South China Sea and violated the consensus both countries have reached on the issue,” China’s Ministry of Foreign Affairs spokeswoman Jiang Yu said late Saturday.

Hanoi said three Chinese marine surveillance vessels approached a ship operated by the state oil and gas firm PetroVietnam and cut its exploration cables, Vietnamese newspaper Thanh Nien reported.

A complaint lodged with the Chinese embassy in Hanoi said the incident “seriously violated Vietnam’s sovereignty” and a 1982 UN convention on the law of the sea, AFP reported.

The Vietnamese Foreign Ministry called on China to prevent any further incidents within what it described as its exclusive economic zone and provide compensation, the Vietnam News Agency reported Friday.

Do Van Hau, a deputy general director of PetroVietnam, was quoted by Thanh Nien daily as saying that PetroVietnam will continue oil exploration in the area because it is Vietnamese territory, and asked for governmental support at the same time.

“What the relevant Chinese departments did were completely normal marine law enforcement and surveillance activities in China’s jurisdictional sea area,” Jiang said.

China is “willing to work together with the relevant parties to seek a solution to related disputes and implement the Declaration on the Conduct of Parties in the South China Sea,” Jiang added, referring to a 2002 agreement between China and the Association of Southeast Asian Nations (ASEAN), in which countries pledged to maintain the status quo in the disputed areas.

Beijing and Hanoi are in an ongoing dispute over the sovereignty of the Xisha Islands and the more southerly Nansha Islands, both potentially resource-rich rocky outcrops in the South China Sea that straddle strategic shipping lanes.

Vietnam has reported cases of fishing boats and equipment being seized by China in the South China Sea since 2009. In March, the Philippines complained that Chinese patrol boats had harassed a Philippine oil exploration vessel in waters near Nansha Islands, and subsequently filed a formal protest at the UN over China’s claims to the Nansha Islands and its adjacent waters.

Brunei and Malaysia also claim all or part of the Nansha Islands.

The situation in the South China Sea became more complicated when the US asserted its interests in the waters last year, emboldening China’s neighbors, according to Bloomberg.

Vietnam and China are negotiating an agreement on a legal framework for solving sea conflicts, Ho Xuan Son, chief of Vietnam’s Ministry of Foreign Affairs’ National Border Committee, said last month on the sidelines of a conference held in Hanoi to review the demarcation of the land border between the countries, according to Thanh Nien.

Su Hao, director of the Asia-Pacific Research Center at China Foreign Affairs University, told the Global Times that Vietnam’s recent moves were an attempt at shrugging off the consensus detailed in the Declaration on the Code of Conduct on the South China Sea.

“Vietnam’s unilateral resources exploration in the South China Sea broke the China-ASEAN consensus. Beijing’s corresponding moves were not in violation of any international agreements,” Su said.

Facing increasing international pressure in the region especially after the US showed its support for Vietnam and other countries, China should stress its presence in the region to protect its own sovereignty and work out solutions though dialogues, Su added.

Last week, China inaugurated its most advanced deep-sea oil platform, which is capable of operating at up to 3,000 meters under the surface of the ocean and is planned to go into operation in the South China Sea.

Li Qian and Xinhua contributed to this story

By Liu Linlin