TORONTO — The presence of 500 Canadian soldiers has already had a notable impact in calming Haiti's notoriously dangerous capital but the threat of violence from armed gangs and militias persists, the commander of the contingent said Tuesday.

In a teleconference call from Port-au-Prince, Lt.-Col. Jim Davis said the gangs, especially those loyal to the country's ousted president, remain active and ominous.

"They possess the capability to perform deliberate, direct-fired actions against the multinational interim force," said Davis.

"That's the underlying threat that we're very cognizant of here, and that we're trying to keep a lid on."

Davis's comments came as the country's former interior minister was arrested in the north on suspicion of orchestrating the killings of several people viewed as opponents of ousted president Jean-Bertrand Aristide.

Aristide fled Feb. 29 after a violent insurgency convulsed Haiti, prompting several countries to send in soldiers to restore order.

Troops from the 2nd Royal Canadian Regiment arrived in Port-au-Prince three weeks ago as part of an interim multinational military force.

Canada initially said it would contribute about 425 soldiers but Davis said the number grew to more than 500 after a needs assessment.

The troops arrived on their 90-day mission to find members of the U.S. force facing nightly attacks.

"As we entered and began to fan out doing our operations, the rival gangs that are in situ (here) were contesting our presence," said Davis.

"Since then, that has subsided."

Most gratifying, he said, is that it has become obvious the troops are bringing stability to the country.

Attendance at schools has increased and people are again going about their daily business.

"We've witnessed the return of Haitians back to their normal daily lifestyles and routines unabated by the previous criminal threats that existed prior to our arrival," Davis said.

The Canadians are patrolling some of the most dangerous parts of Port-au-Prince. The soldiers are responsible for three impoverished districts, where about 200,000 people live in an area the size of Fredericton's downtown core.

A major problem is the huge numbers of weapons in the city. Haitians have the constitutional right to be armed and many are.

"How do you disarm a country, or city in this case, that has the legal right to bear arms for self-protection and self-defence of their home?" Davis said.

Haiti does not have a military and many members of the police force fled the capital when Aristide did fearing for their lives. They have now started returning and have been on joint patrols with the Canadian troops as a confidence builder.

Besides confiscating openly carried weapons and trying to keep the peace, Canadian soldiers are also involved in humanitarian aid: ensuring people have clean drinking water and power and, in some cases, even food.

Soldiers from France, Chile and the United States are also part of the multinational Operation HALO.