Communist Party of India leader Gurudas Dasgupta has warned that the Left parties will be forced to take serious action against the government if Prime Minister Manmohan Singh [Images] failed to heed the sense of the House before signing the 123 Agreement with the United States.

The agreement will operationalise the Indo-US civil nuclear cooperation deal.

Dr Singh had in a statement said that the decision with regard to the agreement was final and there was no question of going back.

"In August 2006, Dr Singh had taken note of the issues raised by the Left parties. What we want him to do now is to take a sense of the House before signing the final agreement," Basudev Acharya of the Communist Party of India-Marxist said.

"If the prime minister does not take notice of the views of the Left parties then we would oppose the agreement tooth and nail and take it to the streets. But this does not mean that we agree with the Bharatiya Janata Party because it was former prime minister Atal Bihar Vajpayee who initiated the discussion on the nuclear deal," another Left leader asserted.

The Left alleged that India was leaning toward imperialist United States which was against India's interests.

"This will harm the interests of India as a nation and its independent foreign policy," Archarya said. The prime minister is scheduled to make a statement in Lok Sabha at 3 pm on Monday.

Parliamentary spokesman of the BJP Vijay Kumar Malhotra said that the Left parties said one thing outside the House and did exactly the opposite while inside the House. "You see what they do when the PM starts making the speech," Malhotra said.