Toronto mayor Rob Ford denied he smokes crack cocaine and said he is not an addict, breaking a week of silence over reports of a video purportedly showing him using the drug.
But critics were not appeased, with one city councillor questioning whether the mayor told "the whole truth" and another calling on him to resign.
The mayor of Canada's largest city did not say whether he has ever used crack.
He told a news conference: "I do not use crack cocaine, nor am I an addict of crack cocaine.
"As for a video, I cannot comment on a video that I have never seen, or does not exist."
Ford's only comments on the scandal before Friday came a week ago, a day after the story broke, when he called the allegations "ridiculous" and said the Toronto Star newspaper was out to get him. Ford said he kept quiet because his lawyer advised him "not to say a word".
The video has not been released publicly and its authenticity has not been verified.
Reports on gossip website Gawker and in the Toronto Star claimed it was taken by men who said they sold the drug to Ford.
The Star reported that two journalists had watched a video that appears to show Ford inhaling from what appears to be a glass crack pipe.
Gawker and the Star said the video was shown to them by a drug dealer who had been trying to sell it for a six-figure sum.
The Star also reported that Ford allegedly made a racist remark about the high school football students he coached.
But Ford criticised the media for judging him. "It is most unfortunate, very unfortunate, that my colleagues and the great people of this city have been exposed to the fact that I've been judged by the media without any evidence," Ford said.
City Councillor Glenn De Baeremaeker said he was profoundly disappointed in the mayor's statement and called on Ford to resign. De Baeremaeker said he believed the reports about Ford's alleged drug use and believes Ford's tenure is over.
"I don't believe the mayor," he said. "He should resign and then go seek help." De Baeremaeker said he had observed erratic behaviour from the mayor. "The mayor is just imploding," he said.
"He had an opportunity to acknowledge that, perhaps, he does have a problem and to take a leave of absence, perhaps to take care of himself and his family. Instead he went on the attack."
Councillor John Parker said Ford's denial was "too little, too late". He added: "I am not sure we've heard the whole truth."