The Left parties on Saturday made a scathing attack on the government for rejoicing the NSG waiver saying it was a "black day" as India's sovereignty had been compromised and its nuclear programme killed.

In a statement, the CPI attacked Prime Minister Manmohan Singh for dubbing the NSG waiver as historic, saying it was "a deliberate attempt to hide the adverse amendments incorporated in the final draft of the NSG waiver".

The NSG has accepted External Affairs Minister Pranab Mukherjee's statement "as a commitment by India to surrender its right for future R&D in nuclear technology, including the right to have strategic programmes.

"Besides, it seems that India has given up its claim on transferring dual use technology," CPI Central Secretariat said, adding that President George W Bush's letter to US Congress made it clear that Washington would never allow sensitive technology for reprocessing and enrichment to be transferred.

"If this has been accepted for NSG waiver, then it is not a historic day but a Black Day for India as far as our nuclear programme is concerned. This waiver will kill our efforts to develop nuclear technology based on thorium," it said, demanding that the government should not proceed with operationalising the 123 agreement till all ramifications of the NSG waiver become clear.

RSP General Secretary T J Chandrachoodan said there was no reason to rejoice as the ground work had been done by the US. "Our objection is to the Hyde Act and we will continue to fight against the nuclear deal."

Forward Bloc leader G Devarajan said the leak of official US correspondence was aimed at getting the "sceptic member countries of NSG to fall in line.