Thousands of residents in northwest China's quake-hit Shaanxi Province are staying in tents after their homes were damaged or destroyed by a seismic aftershock on Tuesday.

A magnitude 5.7 aftershock hit Ningqiang County of Shaanxi around 4 p.m. on Tuesday, leaving at least one injured, 860 houses destroyed and 3,100 damaged, said a provincial government official on Wednesday.

The county is located at the border between Shaanxi and Sichuan Province, which was struck by a magnitude 8.0 earthquake on May 12.

Shaanxi Province set up a quake relief headquarters immediately after the tremor, and ordered residents in Ningqiang and neighbouring counties to be evacuated from dilapidated houses or buildings with cracks.

The headquarter officials also advised people to stay away from high-rise buildings, high-voltage wires and facilities.

It ordered township officials to closely monitor the geological hazards following the tremor and intensify security checks and patrols.

Sources with headquarters said more than 240,000 people, about two-thirds of the county population, were affected by the tremors. About 190,000 people were forced to leave their homes.

The Shaanxi Provincial Seismological Bureau said that by 8:08 p.m. on Tuesday, nine further tremors had been recorded.

Qingchuan County, Sichuan Province, about 100 kilometers from Ningqiang, was also struck by a magnitude 5.4 aftershock at around 4:03 p.m. on Tuesday. More than 60 people were injured and about 400,000 houses collapsed.

Qingchuan was also the epicenter of a magnitude 6.4 aftershock on Sunday afternoon, the strongest since the May 12 earthquake.

The death toll from the powerful earthquake was 68,109 as of noon on Wednesday, the Information Office of the State Council said.

Another 364,552 people were injured and 19,851 others were still listed missing.

(Xinhua News Agency May 29, 2008)