The earthquakes struck about 16km (10 miles) and 15 minutes apart in a sparsely populated area about 84km (50 miles) west of Tibet's capital, Lhasa.

The US Geological Survey said the magnitude of the first quake was 6.6 and that of the second - 5.1.

Many houses collapsed near the epicentre in Damxung county, China's Xinhua news agency says.

Buildings shaken

The area has a population of about 42,000 people, mostly herdsmen.

The director of the Tibetan seismological department, Zhu Quan, says the authorities are still trying to determine the exact number of casualties.

Local officials in Damxung county said more people were still buried under debris.

The earthquake shook buildings in Lhasa, prompting office workers to rush out of their buildings into the street.

However, there have been no reported casualties in the city and damage to buildings is minimal.

Shops remain open and train and air links have not been affected.

The tremors in Tibet - at about 1630 (0830 GMT) - came after a 6.6 magnitude earthquake struck neighbouring Kyrgyzstan, near its border with China, killing at least 65 people.

BBC