Mumbai (Agencies): Sharpening its attack on Prime Minister Manmohan Singh in the 2G spectrum scam, BJP on Sunday charged him with conspiracy of silence, culpable inaction and gross indifference.

At a press conference here, BJP spokesman Ravi Shankar Prasad accused the Prime Minister of being a silent spectator when former telecom minister A Raja flouted his directives for ensuring fairness and transparency in the allocation of spectrum.

He said the Prime Minister was "guilty" of conspiracy of silence, culpable inaction and gross indifference adding that spectrum pricing was kept out of the Group of Ministers (GoM) purview and left to Raja's discretion.

Referring to the controversy over the S-Band spectrum given to Devas, Prasad said it is the second scam under a clean Prime Minister and wondered how no one bothered to question him.

"S-Band spectrum was given only to Devas Multimedia without competitive bidding. The space ministry comes directly under the Prime Minister. How is it that no one bothers to ask the PM. This is the second scam under a clean Prime Minister," he said.

Prasad demanded an explanation from the Prime Minister over the Antrix-Devas deal as to why the government continued talks with Devas till a few weeks ago if the deal was scrapped in July 2010.

He said Devas CEO, Ramachandran Vishwanathan, had said the company was in talks with officials in the PMO till as late as a few weeks ago.

Prasad alleged there was a "hidden hand" to save the deal with Devas Multimedia and said Maharashtra chief minister Prithviraj Chavan, who was the minister overseeing the space department since 2005, owed an explanation.

Hitting out at Congress president Sonia Gandhi for her silence over corruption cases involving the UPA government, Prasad said the country would not tolerate "complete power without any accountability".

To a question on whether the upcoming budget session of Parliament would be a smooth affair, he said BJP was awaiting response from the government over its demand for JPC probe into the 2G scam.

"CBI can not probe how the telecom ministry was always given to the DMK and why the spectrum pricing was taken out of the Group of Ministers preview. JPC can dwell into these aspects. We have put forth our views to finance minister Pranab Mukherjee who told us that he will discuss the matter with the government and get back to us. We are awaiting his response," he said.

Prasad said he differed with senior BJP leader and former telecom minister Arun Shourie's comments that he had informed Arun Jaitley and Sushma Swaraj along with the Prime Minister of the 2G scam in 2007 but the two BJP leaders had kept quiet.

"We raised this issue in Parliament and outside. What the BJP has done over this issue is for everybody to see. I disagree with Shourie's comments," he said.

As regards Shourie appearing before CBI next week, Prasad said BJP has nothing to hide and is open for enquiry.