(UPDATES with new death, injury toll)

by Giles Hewitt

BEIJING, Jan 21 (AFP) - Two major earthquakes hit northwest China on Tuesday, killing at least 12 people and seriously injuring 27 in a province already battered by the worst snow storms in 30 years.

The quakes measured 6.4 and 6.3 on the Richter scale and followed a 5.0-magnitude temblor that struck an isolated area of neighbouring central Tibet on Monday morning, causing no casualties.

The 6.4 quake struck at 9:47 a.m. (0147 GMT) near the Xingiang province city of Jiashi, just 60 kilometers (38 miles) east of Kashgar, and was followed one minute later by the second, a spokesman from the provincial seismology bureau told AFP.

The spokesman said 12 people had been confirmed dead all of them in outlying areas of Jiashi county which has a population of around 260,000.

"These deaths have been reported from isolated villages near the quake area, so we expect the final figure will be higher," the spokesman said, adding that nearly all the deaths were the result of housing collapses.

An eight-year-old child, crushed to death, was among the casualties.

Hundreds of troops and police have been drafted in to help with the rescue work, which has been hampered by the the lack of roads in the area.

Some 20 seismological experts from Beijing as well as the provincial capital, Urumqi, have been sent to the scene, and the local government has warned that further aftershocks with a magnitude as high as 5.0 might hit the area.

Most of the people in Jiashi are Moslem ethnic Uighurs, who make up the majority of Xinjiang's population.

The spokesman added that as many as 1,000 buildings in the immediate area had collapsed.

The epicentre of the quakes was located 20 kilometers (12 miles) north of Jiashi, at longitude 76.55 degrees north and latitude 39.48 degrees east.

An earthquake measuring 6.9 on the Richter scale hit the same area in March last year, killing 24 people and injuring 80.

"The epicentre was much closer this time and the shock more powerful," said a municipal government official in Jiashi, who added that while some buildings in the city had shaken under the force of the quakes, there had been little serious damage.

Xinjiang has been rocked by 10 earthquakes of more than 6.0 on the Richter scale in the past decade.

The strongest, in November last year, measured 7.1 but was centered on the remote and mountainous Karakorum region and resulted in no deaths or damage.

Quakes nationwide have become increasingly frequent since China entered in 1988 its fifth period of heavy seismic activity this century.

Xinjiang is still reeling from the heaviest blizzards in three decades, which have killed at least 36 people, and left as many as 320,000 cut off or trapped by snow drifts.

Twenty-three counties in Xinjiang have been stricken by blizzards, which first hit the autonomous region in late December.

Most of the casualties have come from avalanches that also cut off telecommunication links and power supplies.

Some 183,800 houses belonging to herdsmen have been damaged and economic losses from the disaster have been put at 247 million yuan (30 million dollars).

Xinjiang's mere size its land mass is three times that of France as well as its remote and inhospitable landscape have proved a major obstacle to relief efforts.

Outside of major cities, the region's population most of them Moslem herdsmen is sparsely spread out over vast areas with almost no transport links.