Terrorism charges may be levelled against those responsible for the firebombing of an RBC bank branch in Ottawa once investigators determine the motivation behind the attack, police said Wednesday.

An anarchist group claimed responsibility for the blaze, which broke out in the early hours of Tuesday morning, moments after witnesses saw a group of three or four men fleeing from the scene in Ottawa's trendy Glebe neighbourhood.

Within hours, a video was posted online that showed shadowy figures inside the bank's foyer at about 3:30 a.m. on the morning of the blaze. As the two people dash out the door, a wall of flames flashes inside the bank.

The video is accompanied by a scrolling text message that blames the Royal Bank of Canada for sponsoring the recent Winter Olympics and investing in the Alberta oilsands.

It is credited to "FFFC – Ottawa," a group that promises to be present at the upcoming G8/G20 meetings being held in Huntsville, Ont., and Toronto.

The group claims it will "pass the torch to all those who would resist the trampling of native rights, of the rights of us all, and resist the ongoing destruction of our planet."

Acting inspector Don Sweet of the Ottawa police told CTV's Power Play Wednesday that for now, authorities are conducting an arson investigation into the blaze.

But when asked why the attack is not being investigated as an act of terrorism, Sweet said the investigation could very well head in that direction.

"When we get further at the intent, or if we can get to that, that's when we may expand this and look at other criminal charges when we get to that point in the investigation," Sweet said.

"Clearly based on the target that was hit, the posting that was put out there, the other information we're working on, we are looking towards that part of it. But at the time right now we are in an arson investigation and when we get to that next level, if we do, then we will expand it to include other charges if applicable."

Police will look for and read through any communication between the individuals involved in the attack to determine their motivation.

If they were acting out in anger against the bank, then that is arson, said security expert Tom Quiggin, of the Canadian Centre for Intelligence and Security Studies.

"If, however, their intent is to create a larger atmosphere of fear and intimidation, in it attempts to change what the policy makers think at the G20 or the G8 conference, or to change the direction that the Royal Bank is taking, then that rises to the level of terrorism," Quiggin told Power Play.

Immediately considered to be suspicious, the fire did $300,000 damage to the bank branch that will now be closed for at least a week. Sweet would not comment specifically on whether investigators have identified any suspects in the case. However, the attack remains under investigation by Ottawa police, the Ontario Provincial Police and the RCMP, he said.

The Royal Bank of Canada said it is considering ramping up security in the wake of the incident.

The Canadian Bankers Association said the incident at the Ottawa RBC branch has put its members on alert, but security plans are already in place for next month's G8/G20 meetings.

Anarchist groups hard to peg

Michel Juneau-Katsuya, a former senior intelligence officer with CSIS, told CTV Toronto that the group responsible for the Ottawa bombing is part of a "really small set of groups or people that basically attend demonstrations and cause trouble and cause confrontation."

According to Quiggin, the group may have targeted the bank for a number of reasons in addition to its sponsorship of the Olympics and the torch run.

While Canadian banks have largely emerged from the global financial crisis with their reputations intact, "banks are at the top of the hate list for a lot of international groups: anti-capitalist groups, anti-poverty groups, anti-globalization groups, anti-imperialist groups. All of them are focusing on the role of banks and the role of the international economy. So it puts them at the top of the hit list."

Many protest groups are non-violent in their calls for change -- such as better environmental safeguards, improved financial regulations and increases in development aid -- and so they can often by negotiated with, Quiggin said.

"However, the core group that was behind these kinds of attacks are largely anarchists, and their ambition, if you will, is to smash the state. They want to destroy hierarchical governments and replace them with a government where there's collective decision-making and decentralize power," he said.

"So there's nothing that can be done to placate them directly."

Unlike highly organized terror groups, anarchists are usually poorly organized, devoid of strong leadership and therefore fail to make significant impacts with their protests, Quiggin said.

But that lack of structure makes it hard for police to identify members and turn them against each other.

"So it's sort of a win-lose thing for them," Quiggin said. "The strength is they're harder to track and harder to arrest, the weakness is it's harder to be effective when you're like that."

With files from The Canadian Press and a report from CTV Ottawa's Karen Soloman