The authorities struggled to bring aid to areas worst affected by the 7.6-magnitude quake where key roads were blocked by landslides, power and water supplies were down, and hospitals and schools destroyed.

A senior official said the quake had killed between 30,000 and 40,000 people in the northeast Pakistan, and injured another 60,000.

"It is a whole generation that has been lost in the worst affected areas," military spokesman Major General Shaukat Sultan told AFP. He said the hardest hit area was around the Kashmir town of Muzaffarabad.

In many places people dug with their bare hands in an often futile attempt to reach friends and relatives trapped in the rubble. Anger started to build and sporadic looting broke out as help failed to arrive quickly.

"We survived the earthquake but now we realise we will die of hunger and cold," said Mohammad Zaheer, a resident of the shattered town of Balakot.

In Muzaffarabad, survivors ransacked military trucks which had just arrived in the city and took food, tents, blankets and medicines, an AFP photographer at the scene said.

Others broke into a petrol station to get fuel to burn wood for cooking and warmth.

"Everything is gone, people are buried alive, nobody is helping us to find them," local resident Akram Shah said.

Major General Sultan said the authorities late Monday had succeeded in re-opening the mountain roads leading to Muzaffarabad and Balakot, which had been blocked by landslides, speeding up the relief effort.

International rescue teams with sniffer dogs and specialist equipment have begun arriving in Pakistan and setting up field hospitals to cope with the tens of thousands of injured.

Offers of aid have also begun pouring in from around the world. The United States said it had provided $50 million, the World Bank offered $20 million and the Asian Development Bank pledged $10 million.

Survivors were facing an array of problems -- freezing overnight temperatures, rain, landslides, scarce food, little shelter, no communications networks and almost non-existent healthcare.

The United Nations said more helicopters were needed urgently to bring aid to the hardest-hit villages, most of which are nestled on hard-to-reach forested slopes 3,300 metres high in the foothills of the Himalayas, Karakoram and Hindukush mountain ranges.