Prime Minister Manmohan Singh [Images] has made it clear to Left leaders that the Indo-US civil nuclear deal will not be renegotiated, shortly after the allies rejected the agreement.

Singh, however, conveyed the government's willingness to address the concerns of the Left parties when he spoke to Communist Party of India-Marxist General Secretary Prakash Karat and CPI leaders A B Bardhan and D Raja Tuesday night, highly placed sources said Wednesday.

The prime minister noted that the 123 Agreement, that will operationalise the nuclear deal, has been approved by the cabinet and that there was no question of renegotiating it, sources said.

Singh will make a statement on the issue in Parliament on Monday.

The prime minister's phone call to Left leaders came hours after the four Left parties rejected the agreement, saying that there were many concerns regarding it in context of the Hyde Act.

The Left parties insisted that the agreement fell short of the assurances given by the prime minister to Parliament.

During the telephonic conversation, the Left leaders are understood to have cited reasons for their opposition to the agreement.

The Left parties said they were "unable to accept the agreement" as it "binds" India. They asked the government not to proceed with operationalising the agreement.

The Left parties said "while the Indian commitments are binding and in perpetuity, some of the commitments that the US has made are either quite ambiguous or are ones that can be terminated at a future date."

"A number of the provisions of the Hyde Act pertain to areas outside the nuclear cooperation and "are attempts to coerce India to accept the strategic goals of the US," the Left said.

They particularly referred to the provision in the law that says that India should join the US efforts in isolating and even sanctioning Iran.

The Left joined the Bharatiya Janata Party and UNPA in rejecting the agreement. BJP has demanded scrutiny of the agreement by a joint parliamentary committee.

The party plans to move a motion on the deal under a rule which will force a vote in Lok Sabha.

Former National Security Advisor Brajesh Mishra said the nuclear agreement will make it difficult for the government to carry out an atomic test should such a need arise since economic costs would be "far greater" than in the past.