Amidst a walkout by the Left parties, the government on Thursday asserted in the Lok Sabha that it had the sovereign right to conduct a nuclear test, making it clear that the bilateral agreement with the US does not put any restraint on it.

"There is nothing in the bilateral agreement that the government has entered with the US that will tie the hands of a future government to undertake a nuclear test," External Affairs Minister Pranab Mukherjee said in a brief statement after Left and the opposition members raked up the issue.

The members were protesting against the statement of the US State Department spokesman who had said all nuclear cooperation with India would be terminated if New Delhi carries out a test.

"India has the sovereign right to test and would do so if it is necessary in national interest. The only restraint is our voluntary unilateral moratorium on nuclear testing, declared by the previous (National Democratic Alliance) government and being continued by the successor government.

Mukherjee said nowhere in the bilateral agreement on cooperation for peaceful uses of nuclear energy with the US "is testing mentioned."

He said the agreement contained elaborate provisions in Articles 5 and 14 to ensure the continuous operation of India's reactors.

These include fuel supply assurances, the right to take corrective measures and a strategic fuel reserve for the lifetime of India's reactors in case of cessation of cooperation.

Mukherjee said he was giving the "factual" position.

He said the government still did not have the authentic version of the statement made by the US state department spokesman based on which the members had raised issues in the morning.

While the Left walked out as the minister got up to make the statement, Bharatiya Janata Party and Samajwadi Party members demanded that they should be heard first. The members trooped to the Well of the House and shouted slogans, but the minister continued reading from his prepared text.

Speaker Somnath Chatterjee allowed tabling of the papers and adjourned the House for the day as the din refused to subside.

The House was adjourned twice in the morning after the Left and Opposition members rake up the statement of the US spokesman and demanded the presence of the prime minister to clarify the situation and address their concerns.