"The rebels of 1857 fought for freedom from foreign rule" and to defend "a way of life which they feared the British were destroying," Prime Minister Manmohan Singh said on the eve of 150th anniversary celebrations of the revolt.

The uprising, which helped pave the way for independence 90 years later of the "jewel" in Britain's imperial crown, was a "tribute to traditions of Hindu-Muslim unity," Singh told parliament.

"In the fight for freedom, Hindus and Muslims stood together shoulder-to- shoulder," Singh said. "We cannot forget the Hindu-Muslim unity that 1857 represented and held out as an example for subsequent generations."

The government has been using the uprising as a springboard to promote unity in the country of 1.1 billion people, where religious tensions flare regularly, and there are serious regional, linguistic and caste divides.

"I stand here... to pay homage to the martyrs of 1857. I urge the people of our great nation to ensure their sacrifices are not in vain," Singh said.

"It is our responsibility to build an India marked by harmony between communities, social justice and the equality of all, irrespective of religion, region, language or caste."

Singh's speech came as thousands of banner-waving marchers belting out patriotic songs reached the outskirts of the Indian capital after an 80-kilometre (50-mile) trek from Meerut, where the uprising began.