A total of 187 relocation sites have been established in Dingri and 46,500 people have been moved. The 484 tourists who were visiting the county left the place as of Wednesday noon.

The relief tents are equipped with folding beds, cotton blankets, heaters, generators, stoves and emergency lighting, while people staying there have been provided with coats and warm footwear, besides food and medicine, the official said.

"The area is at a high altitude and is bitterly cold. We need to guarantee basic living conditions for the affected people, keep them warm and help them rebuild their homes as soon as possible," he added.

Hong said that 391 medical workers had been sent to help with the relief work. Among those severely injured, most have head injuries. Others have fractures. The critically injured people have been transferred to Shigatse People's Hospital.

Communication networks and power supplies in the affected area have been restored, he said, adding that the current disaster-relief work will be focused on relocating survivors and completing post-disaster reconstruction.

Tan Xiangdong, deputy director of the Xizang Health Commission, said at the news conference in Shigatse that doctors from Beijing, Shanghai, and Chengdu in Sichuan province have arrived in the region to treat those in critical condition.

Special teams have also arrived to test water quality, disinfect the environment and promote health awareness to prevent an epidemic, he added.

Meng Hui, deputy director of the Xizang Earthquake Agency, said that as of Wednesday noon, 646 aftershocks were recorded, with the strongest being of magnitude 4.4.

He did not rule out the possibility of more quakes of magnitude 5 to 6 over the next few days.