An Indian soldier declared dead has been found alive under 25 feet of snow, six days after he was buried by an avalanche that hit his military post in the disputed Himalayan region of Kashmir.

Rescue teams dug out Naik Hanamanthappa in one of the world's most unforgiving environments, at an altitude of 19,600 feet on the Siachen Glacier, which India and Pakistan have fought over intermittently for three decades.

"We hope the miracle continues. Pray with us," DS Hooda, an Indian army commander, said.

Prime Minister Narendra Modi visited the soldier at a military hospital in the Indian capital, saying he brought "prayers from the entire nation".

The army said the soldier was in a critical condition.

Rescue workers had been searching for almost a week for 10 soldiers who went missing after the avalanche in an area known as the battleground on the roof of the world.

A day after the search began the army said the chances of finding any survivors were "very remote" then said all the other soldiers were now believed dead.