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.