Most of historic buildings in the worst-hit Kathmandu Valley were destroyed in Saturday's powerful earthquake while a 6.7-magnitude aftershock jolted Nepal on Sunday.

The 7.9-magnitude earthquake flattened at least 90 percent of public squares, Buddhist stupas and Hindu temples in the Kathmandu Valley, the state-run Nepal TV reported.

The Kathmandu Valley, listed as the UNESCO World Heritage site, is a collection of seven locations around the Nepali capital that lies at the crossroads of ancient civilization of Asia.

Meanwhile, the U.S. Geological Survey said the strong aftershock, which occurred at 0709 GMT, was centered 31 km southeast of Kodari with a depth of 10 km.

The shallow aftershock lasted about two minutes and was strongly felt in Kathmandu, a Xinhua reporter said.

The death toll from Saturday's massive earthquake has climbed to 1,896, including 723 in Kathmandu.