The Prime Minister Dr. Manmohan Singh has called Home Minister P Chidambaram and is understood to have expressed full faith in his integrity, amid a raging controversy over his stand on 2G spectrum allocation.

During a 20-minute call from Frankfurt where Dr. Singh made a overnight halt on his way to New York, the prime minister discussed with Chidambaram the issue of a 10-page note sent to the Prime Minister's Office(PMO) by the Finance Ministry in March last.

The note that became public after the Prime Minister had left Delhi on his foreign tour suggested that the scam could have been avoided if the Finance Ministry, then under Chidambaram, had insisted on spectrum allocation through auction. The Minister has since been under attack.

Highly placed sources said, the Prime Minister is believed to have counseled Chidambaram to be patient till he returns home from New York on September 27th.

The government on Thursday strongly defended Home Minister P Chidambaram's handling of the allocation of 2G spectrum licenses. Replying to questions on reports of Chidambaram's alleged involvement in the 2G Spectrum scam, Law Minister Salman Khurshid said that Chidambaram did not do anything questionable during his tenure as the Finance Minister.

Mr. Khurshid said that there were no wrong doings by Mr. Chidambaram and government fully supports and stands by him. The Law Minister also stated that the opposition's demand for Mr. Chidambaram's resignation is uncalled for and unwarranted. He accused the opposition of being politically motivated in making allegations against the Home Minister.

The Congress also rejected the opposition demand for the resignation of Home Minister P Chidambaram. Party spokesman Abhishek Manu Singhvi said the party, not in any manner, accepts the allegation made by Subramanian Swamy against him.

Mr. Singhvi said this precise issue has been raised by Dr Swamy in the apex court and is sub judice. But, the BJP has demanded that the CBI should probe the role of P Chidambaram in the 2G scam. Briefing reporters in New Delhi, party spokesperson Rajiv Pratap Rudy alleged that former Telecom Minister A Raja could not have taken all the decisions alone.

The CPI (M) also demanded a CBI probe into the role of P Chidambaram, who was the Finance Minister when the 2G spectrum allocation scam took place. The party politburo in a statement said the evidence has also come to light that a meeting between the then Telecom Minister A Raja and Chidambaram had taken place in January 2008 in which, according to the note prepared by the Finance Secretary, the Finance Minister had stated that they are not going to re-visit the issue of entry fee or revenue sharing.