There were no immediate reports of injuries or damage from the tremors, which came hours before a major United Nations quake donors conference in Geneva.

The heaviest aftershock, with a magnitude of 5.2, came at 6:43 amand there were three weaker tremors between 5:00 am and 9:00 am, Qamaruz Zaman, chief of the country's seismological department, told AFP.

Witnesses said the biggest shock woke people from their sleep in the capital Islamabad and the devastated city of Muzaffarabad.

"An aftershock with a magnitude of more than five can cause landslides in the hilly terrain," Zaman said.

Pakistan has suffered 978 aftershocks since the giant 7.6-magnitude quake, which killed more than 53,000 people in Pakistan. The biggest was on October 9 and measured 6.2 on Richter scale.

"The fear is that landslides will further hamper our operations," World Food Programme spokesman David Orr told AFP in Muzaffarabad.