They said Prime Minister Manmohan Singh's statements on moving the IAEA soon had rendered any further talks on the issue meaningless.

The four parties - CPI (M), CPI, Forward Bloc and RSP - have sought an appointment with President Pratibha Patil for tomorrow morning to submit their letter of withdrawal of support and to demand that the government proves its majority on the floor of the House.

"We will also urge the President to ask the government to prove its majority on the floor of the House," a top Left leader said after the hour-long meeting of the four parties which decided to pull the rug to end their four-and-a-half year relationship with the UPA.

Responding to External Affairs Minister Pranab Mukherjee's suggestion for another meeting of the UPA-Left Committee on the issue, the General Secretaries of the parties said the meeting, proposed on July 10, had been rendered "meaningless" since the Prime Minister had announced that the government would go to the IAEA Board of Governors very soon.

"As you are aware, the Left parties had decided that if the government goes to the IAEA Board of Governors, they will withdraw support. In view of the Prime Minister's announcement, that time has come," CPI(M) General Secretary Prakash Karat told reporters.

In their letter to Mukherjee, the top leaders of the four parties pointed out that the UPA-Left panel had decided that the government would proceed to the IAEA only after it finalised its findings.

"Till now, the 'outcome of the talks', that is the text of the safeguards agreements negotiated with the IAEA Secretariat, has not been made available to the Committee.

Without the text, the Committee cannot come to any finding."

The leaders also accused the ruling Congress-led coalition of "refusing" to provide the text to the members of the Committee and said the proposed meeting on July ten would not serve any purpose in this context.

Karat said "once the text of the safeguards agreement is approved by the IAEA Board, which is what the UPA government seeks to do now, the subsequent steps require no participation at all by the Government of India.

"It is the US government that takes the next steps -- moving the Nuclear Suppliers Group countries for the waiver and then placing the 123 Agreement before the US Congress."

Therefore, Karat said, it was "critical" for the country that the safeguards agreement was discussed with "full transparency and not kept secret".

"Why is the Manmohan Singh government keeping the draft of the IAEA agreement secret from the people of India," the Left leader asked.

In a joint statement, the four Left parties said they had been demanding the full text of the draft IAEA agreement saying it was necessary to see whether "any corrective action is possible on India's part if the US discontinues the fuel supplies".

On the 123 Agreement, which they said contained claims by the US that it would join India in negotiating with the IAEA an 'India-specific fuel supply agreement', the Left leaders said "it is well-known that the IAEA is not at all concerned with fuel supply but only with the imposition of safeguards on nuclear equipment and material."

Hence, they contended that it was important to know how the IAEA safeguards agreement would provide for fuel supply assurances in India's case.

The Left leaders pointed out that the US had suspended nuclear fuel supplies to the Tarapur Atomic power station in 1983 reneging upon a 30-year contract signed in 1963.

"In the present case, the IAEA safeguards would continue even in such a scenario, since they are applicable in perpetuity to the entire civilian nuclear energy sector. The text of the 123 Agreement has very ambiguous references to India taking 'corrective measures' if nuclear fuel supplies from abroad are discontinued."

Reiterating their key concerns regarding the IAEA Safeguards Agreement which have "not been addressed" by the UPA, the Left parties asked if the US or any other NSG country reneged on fuel supply assurances for imported reactors, will India have the ability to withdraw these reactors or the indigenous civilian ones from IAEA safeguards.

They wanted to know what corrective measures India could take if fuel supplies were interrupted by the US/NSG countries and asked what conditions would India have to fulfil if the corrective steps were to be put into operation.