“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.

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 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 UPA-Left Committee on the nuclear deal by March 15 to discuss issues in the wake of US “pressures” to implement the deal.

He criticised 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 supoprt for the deal”.