The 6.0-magnitude aftershock shook the region near the border of Sichuan and Gansu provinces just after 1 a.m., the US Geological Survey said in a preliminary report.  There was no immediate information on the impact of the aftershock.

Thousands of aftershocks have plagued the area since Monday's deadly 7.9-magnitude earthquake, whose epicenter was over Wenchuan county Sichuan province's Wenchuan county.

Meanwhile,  the confirmed death toll from China’s earthquake rose to 32,477, the state-run Xinhua news agency said, citing the government's disaster relief headquarters. More than 198,000 people were injured and about 10,600 others are still trapped in the debris.

Concerns over a damaged dam and rising water levels at two lakes triggered the mass evacuation of 30,000 people in at least 10 villages and townships, Chinese officials said.  People down-river from the quake-damaged Kuzhu dam in Beichuan county were ordered to leave the area on May 17 over fears it might burst, according to Xinhua news agency.

Chinese President Hu Jintao thanked foreign governments and international friends for offering assistance to the quake victims.

Rescue teams from the Republic of Korea, Singapore and Russia have jopined Japanese and Taiwanese experts taking par in the massive search.