China said it is moving a second oil rig to disputed waters claimed by Vietnam, close to the location where ships from the two countries rammed each other in May.
The 600-metre rig is being moved from its current position south of Hainan island to a new location closer to the Vietnamese coast, according to a statement on China's Maritime Safety Administration website.
The statement asked vessels in the area to give the rig a wide berth.
The rig will join another Chinese platform in a disputed part of the South China Sea. China's deployment of the first rig sparked a diplomatic standoff with Vietnam. The countries' navies clashed and anti-China riots erupted across Vietnam, leading to five deaths and extensive damage at scores of factories believed to be Chinese owned.
In fact, most of the factories targeted in the rioting were actually from Taiwan, which is not involved in the current dispute.
The disputed waters are close to the Chinese-controlled Paracel islands, which Vietnam also claims.
Vietnamese and Chinese officials met for talks in Hanoi on Wednesday, although little progress was made.
China's foreign ministry has accused Vietnam of "hyping up" the territorial dispute in the South China Sea.
Speaking to reporters in Beijing, foreign affairs spokesperson Hua Chunying said China had told Vietnam that the presence of the first rig was "completely legal".
Vietnam was told to "stop its interference and harassment, stop hyping up the issue and stop whipping up disagreement to create new disputes", said Hua.
China claims almost all of the mineral-rich South China Sea, but faces competing claims from the Philippines, Malaysia, Taiwan as well as Brunei.