NEW DELHI: India's parliament on Monday opened a special session to debate a coalition government confidence motion triggered by a pull-out of left-wing parties opposed to a nuclear deal with Washington.

Ahead of the debate, Prime Minister Manmohan Singh expressed confidence his government will win what analysts have said will be a tight contest.

"We will prove our majority on the floor of the House," Singh told reporters outside the Lok Sabha, or parliament.

After a day of debate, the confidence vote is expected to take place on Tuesday.

The government will need 272 votes to stay in office.

A loss for the Congress party-led alliance would plunge the world's largest democracy into early elections, and doom a nuclear accord aimed at bringing energy-hungry India into the fold of global nuclear energy commerce.

Singh's Congress party, which is headed by Italian-born widow Sonia Gandhi, maintains it has the support of 290 lawmakers and that it can see through its last year in office.

But opposition parties - including the left and the Hindu nationalist Bharatiya Janata Party (BJP) - are equally confident they can force national elections.

- AFP/yb