Singh raised the issue in Rajya Sabha while participating in a debate on Budget.
As Gadkari was not present in the House, Leader of the House and Finance Minister Arun Jaitley along with IT Minister Ravi Shankar Prasad strongly objected to his statement, saying he was making the allegation in the absence of the Minister and proper notice should have been given.
Though Singh claimed the procedure was followed, Deputy Chairman P J Kurien said he will look into the records and if any violation is found he will expunge the remarks.
Earlier, Singh said, "I demand the resignation of Nitin Gadkari on the floor of the House. He should be dismissed as a Minister after he awarded a single-bid contract to a firm close to his son. I am told that the contract has been cancelled and this means the Government has accepted that a contract was awarded against the rules."
He was referring to the contract awarded for the Zozila pass tunnel to IRB Infrastructure Developers amid strong objections by a number of Ministers.