At least 126 people have been killed in China's Tibet region after a magnitude-6.8 earthquake struck a remote area of the Himalayas along the nation's border with Nepal, according to Chinese state media.

"A reporter learned from the Tibet Autonomous Region earthquake bureau that people have been killed, involving three townships including Changsuo township, Quluo township, and Cuoguo township in Dingri county," Xinhua news agency said.

The news agency initially reported that up to nine people had been killed in the earthquake. By 2pm AEST on Tuesday, that figure had increased five-fold.

China State Media reported at least 126 deaths and 188 injured in Tibet after the earthquake.

Initial reports had the death toll at 53, but it has since increased.