China has accused Vietnamese vessels of ramming its ships near a disputed oil rig in the South China Sea more than 1400 times.

The Ministry of Foreign Affairs said Vietnam has continued to commit “serious infringements” to China’s sovereignty and to make “grave threat to the safety” of Chinese personnel on board the semi-submersible rig Hai Yang Shi You 981.

China National Offshore Oil Corporation (CNOOC) recently the rig into an area near the Paracel Islands – or Xisha Islands as China calls them – in a disputed area of the South China Sea, prompting outrage from the Vietnam government.

There have been tense offshore standoffs ever since, while four Chinese nationals were killed in Vietnam as a wave of anti-China sentiment saw addled crowds descend on Chinese businesses.

“Shortly after the Chinese operation started, Vietnam sent a large number of vessels, including armed vessels, to the site, illegally and forcefully disrupting the Chinese operation and ramming the Chinese government vessels on escort and security missions there,” the Chinese ministry said in a statement on Sunday.

“In the meantime, Vietnam also sent frogmen and other underwater agents to the area, and dropped large numbers of obstacles, including fishing nets and floating objects, in the waters.

“As of 5pm on 7 June, there were as many as 63 Vietnamese vessels in the area at the peak, attempting to break through China’s cordon and ramming the Chinese government ships for a total of 1416 times.”

China maintains that it has “exercised great restraint” in the face of Vietnam’s “provocation”.

“China has conducted over 30 communications with Vietnam at various levels, requesting the Vietnamese side to stop its illegal disruption. Regrettably, however, the illegal disruption of the Vietnamese side is still continuing,” the ministry statement continued.

China and Vietnam both claim the Paracels, while Brunei Darussalam, Malaysia, The Philippines and Taiwan dispute other areas of the South China Sea that China also views as its own.

“The waters between China’s Xisha Islands and the coast of the Vietnamese mainland are yet to be delimited,” the ministry said.

“The two sides have not yet conducted delimitation of the Exclusive Economic Zone (EEZ) and continental shelf in these waters. Both sides are entitled to claim EEZ and continental shelf in accordance with the UNCLOS.

“However, these waters will never become Vietnam’s EEZ and continental shelf no matter which principle is applied in the delimitation.”