The central government is believed to have made yet another attempt to get the clearance of the Left parties to go to the International Atomic Energy Agency for an India-specific safeguards agreement needed to operationalise the India-United States nuclear deal.

Racing against time, the government made the attempt during a meeting between Prime Minister Manmohan Singh [Images] and top Left leaders Prakash Karat and A B Bardhan in the presence of United Progressive Alliance Chairperson Sonia Gandhi [Images] and External Affairs Minister Pranab Mukherjee, sources said.

The Left parties made it clear that this matter could come up only after a debate on the nuclear issue in the ensuing session of Parliament and in the UPA-Left Committee, they said.

The next meeting of the committee, which was scheduled for November 16, has been postponed indefinitely.

The decision-making bodies of the CPI(M) and the CPI-- the politburo and the CPI Central Secretariat respectively -- have been authorised to take "appropriate measures" to ensure that the "next step" on the deal should not be taken by the government.

The Left parties have asked the government not to take the next step in operationalising the deal by starting negotiations on the text of the safeguards agreement with the IAEA.

The CPI(M) politburo begins a two-day meeting on Sunday.