New Delhi/Chennai: The BJP on Sunday attacked the Prime Minister on ISRO Antrix-Devas row, questioning his "silence" and demanded that he must come clean as he holds the Space portfolio while the Congress said that political parties should refrain from commenting on a "legal matter".

"When the ISRO-Devas scandal happened, the Prime Minister appointed two high-power committees. They went into that alleged scandal. We don't know what has come out of these two reports. Even the PM is remaining silent," BJP spokesperson Nirmala Sitharaman said in Chennai.

She alleged that while in the 2G case, Prime Minister Manmohan Singh had sought to put all the blame on coalition politics, the Space Department is held directly by him. She claimed that "governance paralysis" is leading the country nowhere.

"I think the government has a lot of explaining to do. We would definitely demand that the Prime Minister come clean on it. He has to say what was the process adopted in the decision making, who were in-charge when the deal was struck. The Prime Minister remains silent on this issue. He has to give a detailed answer...," the BJP spokesperson told reporters.

Seetharaman sought to know whether only the four scientists blacklisted by the government were responsible for the loss. "Do they have the powers to decide on the deal? Several questions remain unanswered," she said.

The Congress maintained that political parties should not speak on the deal as it is a legal issue.

Congress spokesperson Abhishek Manu Singhvi insisted that the high-powered committee should not be attacked just because its report is in public domain. He agreed that ex-ISRO chief Madhavan Nair has a right to disagree or to criticise.

"It is not for a political party to comment on largely legal matters. It is an issue between the government and Mr Nair. Certainly you have two rival claims about this domain," Singhvi said.

"(But) I don't think anybody has the right to dictate to the government. Certainly it's open for those who do not agree with the report to take appropriate action. But so long the report is there, the government decision is there and it is for them to decide which way to go," he said.