The councillor suspended by Scottish Labour amid allegations of racism and Islamophobia has said he is "stunned" by the claims.
Davie McLachlan, who had been leader of the Labour group on South Lanarkshire Council, said he "categorically denied" making racist remarks to leadership candidate Anas Sarwar and said he would launch a robust defence.
He issued a statement after being suspended by Scottish Labour Party bosses pending an investigation into Mr Sarwar's claims.
The Glasgow MSP, who lost the leadership contest to left-winger Richard Leonard, claimed an elected councillor had told him he could not support him because he was a "brown, Muslim Paki".
He did not initially name the councillor but on Tuesday he met with party bosses and provided them with details in writing as well as disclosing the identity of the councillor.
Mr McLachlan said afterwards: "I categorically deny these deeply hurtful allegations.
"I'm stunned and dismayed at the claims that I would say such things, and I will defend myself robustly in the party's investigation and in any actions that follow.
"Early in the campaign I pledged my support to Anas but later decided to support Mr Leonard. Anas will know this and would understandably be disappointed."
Mr Sarwar earlier explained he had not spoken about the comments during last autumn's Scottish leadership contest as he did not want to be accused of "playing the so-called race card".
Going public with the claims was the "most difficult" thing he had done, the MSP added, but stressed it was also the "right thing to do".
Mr Sarwar has just launched a cross-party group on tackling racism and Islamophobia at the Scottish Parliament.
He insisted that elected politicians "should be held to a higher standard" than the public on such issues.
Speaking about his own experiences on BBC Radio Scotland's Kaye Adams Programme, the Labour MSP said: "In 1997 I was assaulted because of the colour of my skin, in the early 2000s when I was out with my friends on a Saturday night in Glasgow glass bottles were thrown at me because of the colour of our skin.
"That is happening less and that is to be welcomed, we have seen a difference in terms of tolerance and understanding in our communities.
"What my fear is is it now becoming a much more insidious and much more institutionalised form of everyday racism and Islamophobia, and that's what needs to be challenged."
While he did not speak about the issue during the leadership contest, Mr Sarwar said that when setting up the cross-party group at Holyrood "I felt it was right to put my own head above the parapet and talk about my own personal experiences, in the hope we can spark a wider debate".
Mr Sarwar added: "We've got an issue with everyday racism which isn't criminality, most of it can't reported to the police, but impacts upon playgrounds, on college and university campuses, it impacts upon workplaces, and I think as a society in Scotland we should be brave enough to speak about it."