In further hardening of the Left stand, the Communist Party of India on Friday warned the government of withdrawl of support if it goes ahead with the Indo-US nuclear deal.

"Should the government decide to push ahead with the deal, we will not and cannot be a party to go along with it. We will then be left with no other option than to withdraw our support to the government," CPI general secretary A B Bardhan said in a letter to Prime Minister Manmohan Singh [Images].

This is the first time a Left party supporting the government from outside has officially written to the prime minister threatening withdrawal of support though the Left leaders have been making tough statements ever since September when the 123 Agreement was finalised.

CPI, which has 10 members in the Lok Sabha, is part of the CPI-M-led Left Front that commands the backing of 59 members, which is crucial to the government.

Bardhan's missive comes a day after stiff deadline set by CPI-M to the government to convene a meeting of the United Progressive Alliance-Left Committee on the nuclear deal by March 15 to discuss issues in the wake of US "pressures" to implement the deal.

He criticised the prime minister's statements in Parliament on the issue, including his appeal to former prime minister Atal Bihari Vajpayee to rise above party interests saying, "it is an open effort at canvassing BJP's support for the deal".

"Your talk of trying to build a consensus sounds hollow when you are fully aware that no such consensus is possible -- a fact revealed in the Parliamentary debate itself," the CPI veteran said.

Bardhan said certain statements that have appeared in recent days have "greatly disturbed our party".

He said a series of statements from high official US sources have been mounting pressure on government of India to hurry up and sign the Indo-US nuclear deal.

"The latest in the series is the one of Richard Boucher, who by conveying that, 'the nature of the government, minority or caretaker, would be of no concern to the US when agreement is ready to be signed', is in effect telling the government that it should go ahead with the deal, regardless whether it is a minority or caretaker government.

We are shocked that such presumptuous statements go unchallenged," Bardhan said.

He told the prime minister that he knew the stand of the Left parties that the deal would be "totally against our national interests, our sovereignty and independent foreign policy."

"In the midst of this plethora of statements made by the US side and by our own high officials, the solemn decision taken at the last meeting of UPA-Left parties committee that the government will come back to the committee after International Atomic Energy Agency negotiations and even before any text is initialled, is being totally sidetracked.

Public opinion is bewildered at all this. We have been waiting with patience to clarify the situation," Bardhan said.

He said it was not the nuclear deal alone, but many other violations of the Common Minimum Programme which was causing disquiet.

"I have been on tour in Khagaria (Bihar) and Jaunpur (UP) in connection with our state party conferences preceding our party Congress. I am, therefore, faxing this letter to you, and hope that you will give it your serious consideration," Bardhan said.