Montreal police have seized Radio-Canada television footage of a hockey riot Monday night as investigators continue to track down looters and vandals who caused more than half a million dollars damage.

On Wednesday morning, police arrived at the public broadcaster's headquarters in Montreal with a search warrant and seized several tapes of riot footage aired during newscasts on the French-language television network.

Police also asked Radio-Canada to hand over raw footage of the riot that never made it to broadcast, a request the public broadcaster is contesting through its lawyers, but will comply with by submitting tapes in sealed envelopes.

Authorities also seized riot footage at TVA, a private Quebec television network.

The seizures are part of police efforts to identify people behind Monday night's riots, which were recorded, filmed and captured on innumerable amateur videos, cellphones and photos that have surfaced on the internet.

Mayhem broke out in the area around the Bell Centre after the Canadiens won their first-round series against the Bruins.

Celebration turns to rioting

Jubilant celebration on the street took a nasty turn when looters ransacked several stores on St-Catherine Street and attacked police cars, setting several on fire.

Twenty-three people, including three minors, have been arrested so far in connection with the riot.

Sixteen of the suspects, including the minors, were charged Tuesday with several offences including assault, break and enter, theft and public mischief.

The suspects were released after promising to return for their next hearings in May.

Police arrested up seven more suspects on Wednesday and say they expect more will come.

Montreal police Chief Yvan Delorme vowed to review and adjust his force's security plan during home games. 

'Image of Montreal tarnished': mayor

Montreal Mayor Gérald Tremblay said he is proud of the way police handled the rioting crowds, but is terribly disappointed and shocked by people's behaviour, which he says feeds the city's reputation for hockey hooliganism.

"The image of Montreal was tarnished in Quebec and Canada, and throughout the world," he told reporters at the Montreal airport Tuesday night after returning from a trip to Haiti. "Everyone saw those images."

Tremblay said he was surprised at the havoc created. "I've asked the police force all day long, how can events like that happen, given that we've had similar events in the past."

Tremblay said he's open to working with police to rethink game-night strategy, but didn't get into specifics.

"We've got to make sure that we have a strategy that will permit us not to arrest people that are just celebrating, and let's see what we'll be doing in the future. I think that the events of '93 gave us some information," he said, referring to the last hockey riots when the Montreal Canadiens won the Stanley Cup.

Habs 'deeply regret' vandalism

On the eve of their semi-final series opener against the Philadelphia Flyers, the Montreal Canadiens encouraged fans to celebrate in the "traditional spirit of happiness and respect of our sport, that brings us together," said club president Pierre Boivin, in a statement issued on the team's website.

The Habs "deeply regret" the vandalism that happened Monday night and hope future wins won't spark the same reaction.

"The Canadiens' success in the playoffs brings exhilarating moments, and an outpouring of emotions, and we are grateful to our fans for their tremendous support," Boivin said in his statement.

"We ask our fans to show the same public spiritedness as they do in the Bell Centre."

The Habs host the Flyers on Thursday night in the first match of their Eastern Conference semifinal.

Quebec Sports Minister Michelle Courchesne is calling for civility among fans during the next round.

"The Canadiens are playing well," she said. "But we should be very happy, but without violence, without destroying."

"I hope the Canadiens will continue to win," she said. "But I hope we will do that with respect for property."

Montreal Police are asking people who took videos or photos of the riot to send them to authorities. People can submit their material to this email address: coupe.stanley@spvm.qc.ca.