The charges would come at the urging of Gerry McNeilly, head of Ontario's police watchdog, who issued a stinging report this week on G20 policing.
"He believes that there is sufficient evidence against some senior officers, and so he has directed (disciplinary) hearings," said the source, who asked not to be identified because he was not authorized to speak.
"Those (hearings) have to go to the (Police Services) board for approval."
The board has to OK the hearings because more than six months have passed since the officers committed the alleged offences.
Police Chief Bill Blair has not yet asked for the time extension because the complaints against the four or five senior officers only arrived on his desk in the past few days, the source said.
"If the board grants the extension, then people appear at hearings charged with offences under the Police Services Act," the source said.
The specific nature of the allegations were not clear.
In his systemic-review report Wednesday, McNeilly, of the Office of the Independent Police Review Director, blasted police for "blindly" following orders at the G20 that led to the what he called civil-rights abuses, illegal detentions, and the excessive use of force.
He also said he had substantiated more than 100 complaints against individual officers and referred them for hearings, which carry maximum penalties of dismissal from the service on conviction.
Blair noted this week that the police union had lost its court battle to stop the charges from proceeding because the six-month limit had passed.
So far, hearings were already in process for about two-dozen officers.
The June 2010 summit was marred by vandals who smashed windows and set police cruisers on fire as well as by mass arrests, including those of innocent bystanders.
McNeilly's report found police breached constitutional rights during the tumultuous event, in which more than 1,100 people were arrested, most to be released without charge.
He also faulted the incident commander for referring to the crowds at one point as "marauding terrorists" as he followed instructions from the city's now-retired deputy police chief to "take back the streets."
McNeilly took aim at senior officers for failing to address problems at the temporary detention centre in which as many as 1,000 people were held without access to lawyers.
In response, Blair was adamant he would offer no apologies but said officers of all ranks would be held accountable for any proven wrongdoing though Police Services Act hearings.Suggest a correction