A magnitude 7.9 earthquake has struck the Himalayan nation of Nepal, with reports of extensive damages to property and loss of life.

Police said more than 3,000 people were killed in the powerful quake that shook 80km east of Pokhara on Saturday, about half way between the town and the capital Kathmandu.

Of the total, 634 were reported dead in the Kathmandu Valley and at least 300 more in the capital, a police spokesman told Reuters news agency.

The earthquake destroyed many historical landmarks, including the UNESCO World Heritage temples at Basantapur Durbar Square and the Dharara tower, both in central Kathmandu.

The US Geological Survey said the quake hit at 11:56am local time (06:11 GMT). It initially reported a magnitude 7.7 before revising the calculation to 7.5 and later upgraded to 7.9.