The Communist Party of India on Sunday threw its weight behind the ultimatum given to the government by the Marxists not to implement the Indo-US nuclear deal, saying the government would have to pay a major "political price" if it went ahead with the pact.

"They will have to pay a big political price if they are not ready to reconcile with us on the nuclear issue. The Left had its final meeting with the prime minister on the issue yesterday," CPI general secretary Bardhan said.

"What we are saying is do not operationalise this deal. Don't take the first step at all," he said categorically.

Asserting that the nuclear deal should be debated in Parliament, he said, "If the matter is discussed openly in Parliament, then the Congress will realise that they do not have majority support on the issue."

The Left parties will hold a meeting on the issue on Monday and "something concrete will emerge from it", the senior Communist leader said.

"Sarkar ko yeh baat soch kar, samajh kar amal karma chahiye," Bardhan said.

Asked about the components of the draft 123 agreement with the US that the Left objected to, Bardhan said, "The main irritant will be subordinating all our foreign policies and economic issues to American policy.

"Out of this exercise, what we will get is just 20,000 MW of power and that too by 2020. For this we cannot compromise the country's sovereignty and foreign policy."

Bardhan warned the UPA government against beginning negotiations with the IAEA on an agreement on safeguards or with the Nuclear Suppliers Group.

Asked if the government should scrap the draft 123 agreement, he said such deals "need not be scrapped -- they need not be implemented or operationalised".