HAVRES-AUX-MAISONS, Que. - A trial began Thursday for five people charged with violating marine mammal regulations by allegedly coming within 10 metres of seal hunters in March 2006.

Fisheries officer Jean Francois Sylvestre told the court that on March 26, 2006, the Department of Fisheries received a call for help from a sealing boat owned by Jeremy Cyr of Grande-Entree on the Isles de la Madeleine complaining that seal observers were obstructing the hunt.

Sylvestre along with another officer from the Department of Fisheries responded and watch the seal observers.

He said he watched the observers in two inflatable boats and Cyr's boat for between 40 and 50 minutes.

During that time, Sylvestre said, the inflatable boats approached the sealer's boat within the 10-metre limit.

The five defendants -- all critics of the annual hunt off Canada's east coast -- are Canadians Rebecca Aldworth and Andrew Plumbly; Americans Chad Sisneros and Pierre Grzybowski, and British citizen Mark Glover.

They have pleaded not guilty.

The trial is being held before a Court of Quebec judge on the Isles de la Madeleine, the windswept archipelago in the middle of the Gulf of St. Lawrence.

The offence is alleged to have occurred in the southern Gulf, near the Cape Breton coast.

Clayton Ruby, counsel for the five and one of Canada's best-known defence lawyers, said earlier this week before the trial began that he will present video evidence that he says will prove his clients are innocent.

He said federal prosecutors have already dropped an earlier charge of obstructing the hunt. The remaining charge carries a maximum fine of $100,000.

The defendants are representatives of Humane Society International and Humane Society of the United States.

In March 2006, the five had been involved in filming the annual commercial hunt in the Gulf, hoping to capture images of animal cruelty for their anti-sealing campaign.

During the course of their work, RCMP and federal Fisheries officers charged them with violating the 10-metre buffer around sealing vessels and sealers.

The 2006 seal hunt was one of the most turbulent in decades.

Clashes between sealers and animal welfare activists in the Gulf of St. Lawrence and off Newfoundland and Labrador highlighted growing tensions between the people who want to stop the slaughter of young seals and those who rely on it as a much-needed source of income.

High-profile appeals by celebrities, including a widely covered visit to the Gulf by superstar Paul McCartney and the re-emergence of French actress Brigitte Bardot, signalled a massive new effort by animal welfare groups to stop the hunt.