A retired civil servant who firebombed a Royal Bank branch in Ottawa's Glebe neighbourhood in May has been sentenced to 3½ years in prison for arson.

Roger Clement, 58, shown in a court drawing from an earlier appearance, pleaded guilty in November to arson causing damage. He firebombed a Royal Bank branch in Ottawa's Glebe neighbourhood in May. (Laurie Foster-MacLeod/CBC)

Roger Clement, 58, pleaded guilty last month to arson causing damage and mischief in the May 18 firebombing of the Bank Street bank branch.

The court also sentenced Clement to an additional six months in prison on the mischief charge. However, the judge credited Clement with 5½ months for time already served.

Clement said during his sentencing hearing on Monday that the firebombing was a protest against the bank's connections to the Alberta oilsands and the Vancouver Olympics.

Clement poured gasoline in front of the bank's ATM machines while his accomplices ignited the fuel with a Molotov cocktail before running off.

No one was injured in the fire, which caused an estimated $1.6 million in damage.

Clement expressed regret during the first day of his sentencing hearing on Monday over the inconvenience he caused for the "high cost" of his incarceration. He also expressed regret that he will no longer be able to fulfil his obligations to friends and what's left of his family.

The fire at the Bank Street Royal Bank branch on May 18 was recorded on a video posted on the internet, accompanied by a political statement from a group calling itself FFFC - Ottawa. (CBC)

Clement's lawyer, Lawrence Greenspon, told the court on Monday that his client was left to care for a mentally ill brother after his mother died, and both his father and sister committed suicide.

He had argued his client should only serve three years because the attack on the branch at Bank Street and First Avenue was out of character and Clement isn't likely to reoffend.

The Crown had been seeking five to six years.