Disappointed over Union Telecom Minister A Raja's reply to the debate on the functioning of his ministry, the Opposition parties led by BJP on Monday staged a walkout from the Rajya Sabha and insisted a joint parliamentary committee probe into the spectrum allotment.

However, Raja claimed that the allotment was done through the prescribed process.

Speaking in the Upper House, Raja said: "Nothing has been done clandestinely or surreptitiously. I maintain it is most transparent."

The minister informed the house members that the government have so far accumulated Rs 68,000 crore from the spectrum process. In 2007-08 alone the government got Rs 23,000 crore.

In his nearly two-hour reply during the debate, Raja held telecom regulator, Telecom Regulatory Authority of India (TRAI), responsible for the low entry fee.

The union minister also pointed that TRAI is statutory body and it was for it to revisit the issue of entry fee. However, Leader of Opposition Arun Jaitley charged Raja of avoiding the core problem whether the Rs 1,651 crore license fee was a fair value. He described the episode as a "monumental scam" before leading a walkout.

Criticizing the union minister, Jaitely said: "Is the Minister not convinced that Rs 1,650 crore price was under-valued? If he is so convinced that he is not wrong, is he willing to have a JPC as suggested?"

It should be noted here that in 2008, Unitech and Swan - after bagging the licensees for Rs 1,651 crore each - sold stakes to foreign partners at huge premium leading to an outcry over alleged under-valuation of Spectrum.