NEW DELHI: Congress today demanded sacking of Union Minister Nitin Gadkari accusing him of awarding a single-bid contract of Rs 10,500 crore to a firm for the Zoji La pass tunnel in the Kashmir Valley in violation of the CVC guidelines."I am told that the contract has since been cancelled and this means the Government has accepted that a contract was awarded against the rules," party general secretary Digvijay Singh told reporters, adding Gadkari should resign or he should be dismissed as a Minister.Virtually daring Gadkari for a public debate, he said the Union Minister should come clean on the issue.Singh said that he is going to write to the Chairman of the Parliamentary Standing Committee, Ministry of Highways and Road Transport , to particularly examine this case which, he alleged, is a "symbol of corruption" in the NDA government.Singh, a known detractor of Gadkari, also sought to raise questions about an OSD of the Minister.Gadkari has earlier rubbished the charges of corruption and had said Singh's allegations were "completely false" as the Ministry followed a transparent e-tender system.He had also denied that his son was a director in IRB Infrastructure Developers Singh wondered as to why the name of the OSD, earlier a Superintending Engineer in Maharashtra, has been taken out of an FIR in a corruption case in that state even when the "ACB Nagpur had found him guilty".Singh alleged that instead of "crony capitalism", there is "crony nexus" between the engineer and the Minister "that stands established".