Lawmakers supporting the legislation on the Indo-US nuclear deal on Saturday described it as a 'bipartisan effort' recognising the nuclear reality of India, while its opponents termed it a 'historic mistake' that may trigger an arms race.

During a spirited debate in the House of Representatives on the legislation, which was later approved overwhelmingly, the new Democratic Chairman of House International Relations Committee Tom Lantos said, "This is a historic day for this House and for the United States."

"This truly bipartisan effort is an excellent step forward. It recognises the nuclear reality of India," said Henry Hyde, the outgoing Republican Chairman of the Committee.

Democratic lawmaker Ed Markey, who vehemently opposed the legislation said the bill was a 'historic mistake.'

Holding up a large picture of Pakistan's disgraced nuclear scientist A Q Khan, Markey said: "A Q Khan would accept a deal like that for Pakistan."

"What are we going to say when China offers the same deal to Pakistan? What will we say when the Russians offer the same deal to the Iranians," he questioned.