In a statement, Chief Bill Blair lashed out at Coun. Doug Ford, for making the comments.
"Doug Ford is lying," Blair said through his spokesman, Mark Pugash. "I am prepared to take legal action."
Pugash refused to elaborate on the legal threat.
Earlier Friday, the Toronto Star cited sources as saying police were about to subpoena the mayor to testify at the preliminary hearing for his friend Alessandro (Sandro) Lisi, who faces drug and extortion charges.
In response, Coun. Ford suggested the leak — which he blamed on the chief — was politically motivated.
"Rob's changed his life. I just hope the top-ranking person in the police would change his life and follow the rules," Doug Ford told the Globe and Mail.
Speaking later to reporters at city hall, Doug Ford continued his attack.
"When you tell the media there's a subpoena and don't tell anyone else? That alone says it all right there. That says it all."
Ford refused to elaborate on what he meant by "payback."
"That's my opinion. You know exactly what I'm talking about," he said.
"It's disappointing that the police chief, in my opinion, would condone this behaviour from his own department."
The mayor has yet to be served with the subpoena, his brother said.
"Maybe the chief should just let the Toronto Star serve him, because God knows, they've got a direct line to the chief."
This week, the city's police services board announced that it would not extend Blair's contract again, effectively terminating his position as of next April.
Both Fords have repeatedly claimed that an ongoing police investigation of the mayor is politically motivated.
Blair found himself the target of the mayor's anger over the police probe that turned up a video apparently showing him smoking crack cocaine. At a news conference last October, Blair said he was disappointed at what it showed.
Ford, who later admitted to smoking crack cocaine in a "drunken stupor," has publicly accused Blair of wasting taxpayers' money with the investigation and challenged the chief to arrest and charge him.
The mayor also made disparaging comments about Blair during a videotaped tirade he said happened when he had been drinking.
Blair called the profane rant "disgusting" and "shameful."
The mayor confirmed Friday that he has yet to be served with a subpoena but refused to discuss the issue.
"This is not news," he said.
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