Toronto's police chief says a professional standards investigation has been launched after an officer wrote a scathing letter accusing Mayor John Tory of contributing to the city's gun violence by cancelling a special police task force created in the wake of the 2005 Summer of the Gun.

Mark Saunders says in a statement issued Friday night that the officer — who he does not name — will be disciplined if he is found to have committed misconduct.

The letter from Mark Hayward, addressed to Tory and first reported by Global News, blames the mayor for the decision to cancel the Toronto Anti-Violence Intervention Strategy (TAVIS) in 2016, which the letter says deprived police of a crucial tool in keeping violent street gangs at bay.

In the letter, Hayward calls Saunders "a puppet on strings," which he says are pulled by the mayor.

Saunders says there are "conflicting points between what has been reported in the media [about the letter] and what our investigation has uncovered," but he does not expand on what those points are.

He says TAVIS was cancelled as part of a modernization effort that includes 32 recommendations from members of the public and "highly trained members of the service."

Saunders says the force remains steadfastly focused on its effort to curb violence, and "will not be distracted by those who are trying to hinder our modernization efforts."

Hayward declined to comment on Saturday, citing the internal investigation.

In a statement Saturday afternoon, Tory says he supports Saunders and the city's police services board "100 per cent," and he blames the head of the police union for what he calls "a dangerous set of tactics."

Mike McCormack "could be a partner with us in our fight to rid our streets of the gun violence we've seen recently," Tory says, adding, "Unfortunately, he has chosen not to be."

Tory accuses McCormack of holding up shift schedule changes that would allow the city to "deploy more officers where we need them."

McCormack did not mince words in responding to the mayor's statement, calling it an attempt to distract from the surge of shootings that has gripped the city in recent weeks.

"He's deflecting towards me. Well, I got big shoulders — so be it," McCormack said in a phone interview Saturday.

"But that's really not helping the dialogue."

Regarding Tory's allegation that McCormack had held up changes to shift schedules, the union head was equally blunt.

"You can't deploy officers you don't have," he said.

"We just don't have the resources, and the mayor knows that."

He said hundreds more officers are needed to deal with the issues the city faces.