Story highlights China completed a drilling operation near the Paracel Islands between May 2 and July 15

The area has potential for oil exploration and is contested by China and Vietnam

China recently deported 13 Vietnamese who were arrested for fishing in Chinese waters

Signs of oil and gas have been found by a Chinese rig that was drilling off a disputed island chain in the South China Seas, according to Chinese state media

The drilling area does have the basic conditions and potential for oil exploration, Wang Zhen, deputy director of CNPC Policy Research Office, told Xinhua.

The drilling operation, known as the Zhongjiannan Project, was completed on July 15, according to the China National Petroleum Corporation (CNPC) . The state-owned energy company will further analyze the collected geological data before announcing their next steps.

When China dispatched the oil rig on May 2 to begin drilling near the Paracel Islands in the South China Seas, the move kicked off a series of confrontations between Chinese and Vietnamese vessels in the area. Both nations claim ownership over the chain China refers to as the Xisha islands.

Rioting

Clashes at sea sparked violent anti-Chinese riots on land. Thousands of Chinese nationals had to be evacuated from Vietnam in mid-May as the demonstrations turned deadly.

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In the face of Vietnam's ferocious protests, Beijing has stood its ground on its claim over the Paracels.

China's Ministry of Foreign Affairs spokesperson Hong Lei emphasized this on Wednesday.

"The Xisha Islands are integral parts of China. The operation by the Chinese company is located in indisputable coastal waters of the Xisha (Paracel) Islands, which falls well within China's sovereignty," said Hong.

Xinhua also reported that 13 Vietnamese fishermen previously arrested by the Chinese coastguard were deported on Tuesday. The fishermen were accused of operating illegally in Chinese waters off the coast of Hainan Province.

Vietnam continues to reject China's claims to the Paracels, calling recent drilling activities "illegal" and in violation of international law.

According to CNOOC, a third of China's oil and gas resources are under the South China Sea, most of which it claims as its own, refuting rival claims from Vietnam, the Philippines, Taiwan, Malaysia, and Brunei.