The quake had a magnitude of 7.6 on the Richater scale and its epicentre was 50 miles north-northeast of Pakistan's capital, Islamabad. Media and military sources there reported the expected toll .
Several villages in northern Pakistan were buried in landslides, said Maj. Gen. Shaukat Sultan, the Pakistani army's chief spokesman. He said: "The damage and casualties could be massive and it is a national tragedy. This is the worst earthquake in recent times."
Part of a 10-storey apartment building collapsed in Islamabad, and dozens of people were feared trapped.
Extensive damage was reported in the Himalayan territory of Kashmir, divided between rival neighbours India and Pakistan.
Residents in Kabul, the capital of neighbouring Afghanistan, felt the quake, fleeing their homes for fear they would collapse.
The tremors affected northern India, and were felt in Bangladesh
Police in Lahore said at least eight people were injured and four shops were damaged. The earthquake also damaged part of a school in Rawalpindi, a city near Islamabad, injuring two girls.
In Islamabad, buildings shook and walls swayed for about a minute at 8.50am local time (4.50am BST).
US military spokesman Lt Col Jerry O'Hara said the quake was felt at Bagram, the main American base in Afghanistan, but he had no reports of damage at bases around the country.
UK emergency workers are on standby to fly to the south Asian sub-continent after a huge earthquake rocked the region today. A spokesman for the UK Department for International Development (DFID) said: "At this stage, we are still gathering information.
"UK search and rescue teams have been put on standby. We are just waiting to get a better assessment and sort our response."
The UK team is to include the International Rescue Corps, who said in a statement: "The International Rescue Corps has put a team on standby to assist in the search and rescue efforts following the earthquake in Pakistan today.
"The corps will continue to monitor the situation."
The charity Oxfam is currently beginning an assessment in the affected region, and is to meet other aid agencies and the United Nations later today to co-ordinate a response.
Jane Cocking, Oxfam's earthquake response co-ordinator said: "Oxfam's humanitarian response co-ordinator is now in Pakistan and is on his way to Islamabad to carry out an initial assessment.
"Oxfam's aid workers in Islamabad report some damage in the centre of Islamabad but there are fears that more remote areas outside of the city will have been more seriously affected.
"Oxfam will be meeting with other aid agencies and the UN later today to co-ordinate our initial response.
"As well as rescuing those trapped by the earthquake, the top priorities will be ensuring the survivors have emergency shelter, food supplies, drinking water and basic sanitation, all of which will have been affected by the earthquake. "Reuse content