The telephone call last night lasted 20 minutes during which the Prime Minister is believed to have expressed full faith in the integrity of the former Finance Minister and that he was ready to say this, according to sources today.
The sources said the prime minister also counselled Chidambaram to be patient till he returns home from New York on September 27.
The "secret" note was not shown to him, Singh is believed to have told Chidambaram, who was the Finance Minister during 2G spectrum allocation.
The March 25, 2011 document on allocation and pricing of 2G spectrum broadly suggests that Chidambaram could have insisted that the valuable resource could have been auctioned at the time the spectrum was sold on a first come, first served basis by the former Telecom Minister A Raja, now behind bars.
The note submitted to the Supreme Court on Wednesday was written by PGS Rao, Deputy Director in the Finance Ministry, to Vini Mahajan, Joint Secretary in the PMO. The covering letter to the note also said that Finance Minister Pranab Mukherjee had seen the note.