TORONTO -- The senior police officer who ordered mass detentions and arrests at the G20 summit in Toronto six years ago has been reprimanded and will lose 30 paid days.

Supt. David (Mark) Fenton was sentenced today.

A police tribunal convicted him last year of exceeding his authority and discreditable conduct.

The 28-year officer was in charge when hundreds of people were detained illegally during the tumultuous weekend summit.

Those detained or arrested had asked for the officer to be fired.

The prosecution wanted a year-long demotion, while the defence had asked for a reprimand or the docking of vacation pay.

"He was motivated by fear," said retired justice John Hamilton, who oversaw the misconduct tribunal.

"The fear did not justify the actions taken but it was relevant to Fenton's motivation...the protection of property, the public and the G20 delegates."

Fenton, in full dress uniform, did not immediately say anything after Hamilton announced the sentence.

The G20 weekend was marred by a spate of vandalism in which store windows were smashed and two cruisers set alight. About 1,100 people -- most peaceful protesters or innocent passersby -- were detained or arrested. Many were held in deplorable conditions at a makeshift detention centre.

At the time, Fenton described the protesters as a "marauding group of terrorists."

Fenton's conduct was "condoned by his superiors," who were well aware of what he was doing, Hamilton said in sentencing. In fact, Hamilton noted, he was later commended by then police chief, Bill Blair.

"His misconduct occurred under the noses of his superiors," Hamilton said. "He should have been stopped by his superiors. That never happened."

In his earlier 150-page decision, Hamilton convicted Fenton after finding the officer had no reasonable grounds to order the detentions, in one case just minutes after coming on shift. Hamilton also said Fenton's testimony was not credible.

During sentencing arguments earlier this year, lawyers for the complainants said Fenton, 56, had shown no remorse and had tried to blame everyone other than himself for the trampling of civil liberties. They said he deserved to be fired for upending the Constitution and turning the downtown core into a police state.

"Dismissal would be inappropriate," Hamilton said, saying his long exemplary career should not be judged for two mistakes made over a trying weekend.

The prosecution had wanted a one-rank demotion for one year at a cost of about $15,000 in lost pay, but Hamilton said even that would be too harsh, and punish his subordinates.

Fenton's lawyer, however, argued the demotion would cost as much as $45,000 in lost wages and pension and said it would be unfair to hold his client accountable for what he called the failings of an entire senior command that had no idea how to contain the violence.

He asked for a reprimand or forfeiture of several days pay.