Biswas, a Rajya Sabha member told reporters "This is the unanimous decision of the four Left parties -- CPI(M), CPI, RSP and Forward Bloc.

"The Congress-led UPA Government is committed to the US on the 123 Agreement surrendering national interest and sovereignty. The decision to withdraw support is unchanged," he said.

Biswas who spoke to CPI(M) General Secretary Prakash Karat over telephone during the day, said the decision of he withdrawal of support would be irrespective of the reply from External Affairs Minister Pranab Mukherjee to the letter of the left parties.

He said, "Mukherjee might propose another meeting, but that will not change our decision."

Besides the issue of nuclear deal, the letter would also highlight rising prices and inflation as the reasons for the withdrawal of the support.

He said the four left parties would meet tomorrow to take stock of the situation and find a "political alternative".

Left deadline on N-deal ends; Govt proposes another meeting

Responding to the Left parties' letter asking the government whether it was moving the IAEA to formalise a safeguards agreement on the Indo-US nuclear deal, the Congress today proposed another round of meeting of the UPA-Left Committee on the issue on July 10.

External Affairs Minister Pranab Mukherjee, who heads the Committee, wrote a short reply to the Left leaders suggesting another round of meeting on Thursday, as the outside supporters decided to meet here tomorrow to chalk out their future course of action.

"We have received the letter. We will meet tomorrow to decide on the future course," CPI(M) General Secretary Prakash Karat said..

Leaders of the other three Left parties also confirmed having received Mukherjee's letter.

RSP General Secretary T J Chandrachoodan said "the letter is non-committal. We will discuss it tomorrow." CPI National Secretary D Raja also said the Left would decide on its future moves at tomorrow's meeting.

The Left parties have decided to withdraw support the moment the government proceeds to the IAEA to finalise the India-specific safeguards agreement which they feel would be a step towards operationalising the Indo-US nuclear deal.

The outside supporters, who have a strength of 59 members in the Lok Sabha, had set the deadline till July 7 for the ruling coalition to clarify whether it was going to the IAEA.