Senior Bharatiya Janata Party leader L K Advani on Wednesday demanded that Prime Minister Manmohan Singh should immediately respond to the Supreme Court's observation on the delay in the prosecution of former telecom minister A Raja in the 2G spectrum allocation issue.

"The PM should immediately respond to what the Supreme Court has said on Raja issue," Advani told reporters before leaving for campaigning for the last phase of Bihar assembly elections.

He said, "We are demanding a probe by a joint parliamentary committee into the issue in Parliament and the government should think about it."

"I don't remember the SC raising a question like this in 60 years of my parliamentary career," Advani said.

The Supreme Court had on Tuesday asked some embarrassing questions about the lengthy delay on the part of the prime minister in taking a decision on a plea for sanction of prosecution of the former telecom minister in the controversial 2G spectrum allocation issue.

"Can the sanctioning authority (the prime minister) sit on the complaint," a bench of Justices G S Singhvi and A K Ganguly had asked during a hearing on a petition filed by Janata Party President and former law minister Subramaniam Swamy, who had sought sanction for the prosecution of Raja.

Advani said during the last two sessions of Parliament, "price rise and inflation were one of the main issues, and the way the Opposition raised it, the government was forced to debate on it".

He said corruption has now become an important issue as three major scams had surfaced.