The Liberhan Commission on Monday summoned former Uttar Pradesh chief minister Kalyan Singh as a witness, but rejected a plea to summon Prime Minister Atal Bihari Vajpayee and his deputy Lal Kishenchand Advani to examine their alleged role in the conspiracy to demolish the disputed structure in Ayodhya.

Directing Singh to depose as commission's witness on August 7 and 8, Justice M S Liberhan said the former chief minister is a 'pivotal witness' and it is in the public interest that the truth be unveiled.

Singh has not yet appeared as a witness before the commission contending that his appearance would prejudice his defence in the CBI case on the demolition pending in trial courts.

The former Uttar Pradesh chief minister had recently said he was prepared to appear before the commission and 'expose' the role of Vajpayee, Advani, BJP and Sangh Parivar leaders in the alleged conspiracy to demolish the disputed structure.

"There can be no doubt that Kalyan Singh is a pivotal witness, especially in the context of rumours or reports about a conspiracy and if there is any conspiracy by whom, apart from questions of security, mobilisation of movement, etc. The matter can be more fully, effectively and justly gone into after recording the statement of Kalyan Singh," the commission said.

Singh, however, declined to say if he would appear as a witness.

Singh, who was the chief minister when the disputed structure was demolished on December 6, 1992, said that he has not yet seen the exact text of the decision of the commission to summon him as a witness.

"I shall make comment only after consulting my lawyers," he said.

Singh had earlier said that he would depose before the Commission only if Vajpayee and Advani were also summoned to appear before the panel on the same day.