An oil rig that China moved into contested waters to the fury of Vietnam has finished drilling "as planned", the energy company behind the project said, a month earlier than expected.
The official news agency Xinhua said the giant rig would be withdrawn to the area of China's Hainan island.
Relations between the Communist neighbours have plummeted since the oil rig was moved near the Paracel Islands in the South China Sea in May.
Beijing and Hanoi are embroiled in a bitter territorial dispute over claims in the area, and there have been repeated skirmishes between dozens of Chinese and Vietnamese vessels since the rig was deployed, along with a wave of deadly anti-Chinese riots in Vietnam.
"The mission has been completed smoothly as planned, and oil and gas has been discovered," a statement from China National Petroleum Corp (CNPC) posted on its website late Tuesday said.
"The data collected will be analysed and a decision made on the next step," the statement added.
The statement did not give any indication of the quality of the reserves, or how they could be exploited.
China previously said the drilling would continue until August 15.
China is embroiled in a series of disputes with its southeast Asian neighbours over its expansive claims to the South China Sea.