Indian authorities will demolish some buildings in a northern Himalayan town near the China border after evacuating families in the past few days, an official said on Tuesday, as hundreds of houses developed cracks in the area popular with pilgrims.

Experts and residents have long warned that large-scale construction work in and around Joshimath town, including for power projects built by companies like state-run NTPC, could lead to land subsidence.

NTPC, India's largest power producer, says its tunnelling and other work is not responsible for the cracks in the town of about 17,000 people.

Joshimath is a gateway to Hindu and Sikh shrines and is popular with tourists looking to trek parts of the Himalayas.

Nearly 700 houses in the town in Uttarakhand state have developed cracks and some 400 people have been moved to safer locations, authorities say.

"Six structures from across four wards have been found very unsafe," Himanshu Khurana, a top official of the Chamoli district where Joshimath is located, told Reuters. "We will demolish some unsafe buildings based on the recommendation and under the guidance of federal experts."

Two buildings have been identified already for demolition, he said, without clarifying when that could happen.

Khurana earlier told Reuters that work on some border road projects as well as NTPC's Tapovan Vishnugad 520 megawatt hydro power plant had been suspended.

Local resident Prakash Bhutiyal, 50, said seven of the 11 rooms in his residence-cum-guesthouse had developed cracks and they were waiting to be moved to a safer location.

"Our family of nine has been forced to live in just one room," he said. "We have kept all our belongings in the open. We are yet to be shifted to a safer place." (Writing by Sudipto Ganguly in Mumbai; editing by Michael Perry)