OTTAWA/MONTREAL (Reuters) - A Canadian airliner with 54 passengers on board had to swerve to avoid an unmanned flying object near Toronto early on Monday, slightly injuring two cabin crew, in the most serious case of its kind in Canada, officials said.

The Porter Airlines Bombardier Q400 plane, which took off from Ottawa, was at 9,000 feet (2,750 meters), descending into the city’s Billy Bishop waterfront airport, when the pilots saw an unmanned aerial vehicle.

“Two crew members performed an evasive maneuver to avoid the unidentified object,” said Genevieve Corbin, a spokeswoman for the Transportation Safety Board of Canada (TSB). Corbin said the object was most likely a drone.

Two cabin crew suffered slight injuries during the incident, Porter said.

“The pilots’ initial assessment was that it looked like a balloon. After debriefing, there is potential that the object was a drone,” said Porter Airlines spokesman Brad Cicero.

The plane landed at about 7:30 a.m. ET. The TSB has now launched an investigation, the first time it has done so for such an incident, said Corbin.

Dan Adamus, president of the Air Line Pilots Association International’s Canada Board, said by phone that he had never heard of a plane swerving to avoid a drone in the country before.

“This is a big concern for pilots,” he said.

In June, Canada’s Transport Ministry launched a campaign intended to deter people from flying drones near airports or aircraft.

In Canada, users operating drones weighing less than 35 kg (77 lbs) for recreational purposes do not need a permit.

Transport Canada, however, is now proposing to end the distinction between flying drones for recreational and commercial purposes, and would instead regulate the use of UAVs based on risk by looking at factors like the size of the drone and whether they are flown in the line of sight.

“We are looking at the rules and regulations that are in place now, and we are looking to strengthen them because it is in fact – it can be very dangerous,” Kate Young, Parliamentary Secretary to Canada’s Minister of Transport told reporters on Monday.

There have been a rash of near misses between planes and unmanned aerial vehicles in the United States in recent years.

In April, police in Britain said a British Airways passenger aircraft collided with what was most likely a drone as it prepared to land at London’s Heathrow Airport.