The number of dead in a magnitude 6.8 earthquake that struck the Tibet Autonomous Region in western China has risen to at least 126.

The tremor also left 188 others injured.

Authorities have raised the earthquake emergency response to the highest level, the region's emergency command centre announced on Tuesday.

The earthquake struck at 9.05am, and the epicentre was in Tsogo Township of Dingri County.

More than 1,000 houses were damaged in the strongest tremor to hit Dingri in five years.

Many people were trapped as dozens of aftershocks shook the remote region.

President Xi Jinping has ordered all-out rescue efforts to save lives.

Vice Premier Zhang Guoqing led a team to the quake site, and thousands of rescuers and medical workers have been sent to the area.

People in northeastern Nepal also felt the earthquake, but there were no initial reports of injuries or damage.

Meanwhile, Chief Executive John Lee said the Hong Kong government will maintain close contact with relief organisations and provide assistance through its Disaster Relief Fund to those affected in Tibet.

He expressed deep condolences to the victims and their families.

Lee added that authorities have not received any requests for assistance from Hong Kong residents so far. (Additional reporting by Xinhua, agencies)