The Left parties will submit a detailed note on their objections to the Indo-US nuclear deal to the United Progressive Alliance-Left committee on Friday.
The contents of the note were finalised at a meeting of the four Left parties in Delhi on Thursday.
The note will spell out their opposition to the deal in the context of the Hyde Act and its implications for the country's foreign policy.
Left leaders said they were expecting a reply from the government side on Monday, ahead of the second meeting of the UPA-Left committee on Wednesday.
"We discussed the points on which we will prepare our note," CPI general secretary A B Bardhan told reporters after the meeting.
Forward Bloc general secretary Debabrata Biswas said the note would be sent to the committee on Friday.
"The reply from the government should come to us by September 17. Then the committee will meet on September 19," he added.
He said "the committee itself has noted our concern and we will elaborating on some of the issues."
Besides Bardhan and Biswas, the meeting was attended by CPI-M general secretary Prakash Karat, senior leader Sitaram Yechury, CPI secretary D Raja and Revolutionary Socialist Party leader Abani Roy.
The UPA-Left Committee has already decided to discuss the implications of the Hyde Act on the 123 agreement and on self-reliance in India's nuclear sector at its next meeting on September 19.
Besides the implications of the Hyde Act, the 15-member panel will also discuss the implications of the deal on the country's foreign policy and security cooperation.
At the first meeting of the committee on Monday, its convenor and External Affairs Minister Pranab Mukherjee had given a two-page note to the Left leaders identifying their possible objections to the deal and the government's stand on them.