Vietnam has made "brutal and unjustified disruptions" to China's normal, legitimate oil rig drilling and has unilaterally established dozens of drilling platforms in disputed waters, a senior Chinese diplomat said on Friday.

Ouyang Yujing, director-general of the Chinese Foreign Ministry's Department of Boundary and Ocean Affairs, told reporters that Vietnamese vessels have instigated collisions with Chinese ships in waters around a Chinese oil rig 510 times since May 2.

On May 13 alone, as part of Vietnam's harassment and intimidation, the Vietnamese vessels rammed Chinese ships 169 times, while the Chinese were present solely for the protection of Chinese facilities and personnel, he said.

"Vietnam is playing the writer, director and actor all at once in a self-victimization show, portraying itself as the innocent victim," Ouyang said.

Anti-China looting and arson spread through Vietnam after ships and personnel from the country repeatedly harassed oil rig operations in waters off China's Zhongjian Island.

The Vietnamese Foreign Ministry said on May 7 that Vietnam "cannot accept China's illegal drilling rig HD-981" and "it is an infringement of Vietnam's sovereignty".

The rig is in waters only 17 nautical miles (27 kilometers) from Zhongjian Island, a part of the territorial Xisha Islands in the South China Sea.

By contrast, the drill is about 150 nautical miles (241 kilometers) from Vietnam's coast.

"Therefore, no matter which principle is applied in the delimitation, the waters in question can never become part of Vietnam's exclusive economic zones or continental shelf," Ouyang said.

He also pointed out that the Chinese drilling operation did not start "just this year or this month".

Foreign Minister Wang Yi said earlier this week that the normal oil drilling activities near the Xisha Islands and their contiguous zone "started 10 years ago".

"In May and June last year, a three-dimensional seismic operation and well site survey was also conducted by the Chinese company in these waters," Ouyang said.

But Vietnam has continued its oil and gas exploration and development activities in the disputed waters with China in the South China Sea over the years, he said.

"It is estimated that Vietnam has designated 15 oil and gas blocks in the disputed waters, with seven fields in production and 37 drilling platforms," Ouyang said.

Li Guoqiang, deputy director of the Center for Chinese Borderland History and Geography at the Chinese Academy of Social Sciences, said Vietnam is a major beneficiary of the oil and gas resources buried in the South China Sea.

"It has taken years to boost its strength - politically, militarily and diplomatically - in justifying its claims and challenging other parties on the sea issue," Li said.

It is not that China is unable to obstruct Vietnam's operations, but China has "exercised great restraint" in consideration of the overall bilateral relations and peace and stability in the South China Sea, Ouyang said.

Li warned the harassment by Vietnam is "posing a huge threat to regional stability".

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