The testing program for Bombardier's upcoming CSeries jets has been temporarily halted after what the company called "an engine-related incident" on one of the test planes during maintenance work in Mirabel airport north of Montreal.

A company spokesman said there were no injuries and testing will resume pending an investigation by the company, engine-maker Pratt & Whitney and Transport Canada.

Canada's Transportation Safety Board sent an investigator to the scene to gather information and assess the incident.

The nature of the incident in that occurred late Thursday afternoon in Quebec wasn't immediately disclosed, but firefighters from Mirabel airport responded to a call.

"We remain focused on meeting the CSeries aircraft development schedule and entry into service in the second half of 2015, but safety is the priority," Marc Duchesne said.

Montreal-based Bombardier, the world's third-largest maker of civilian commercial aircraft, has said it hopes to capture half the global market of the 100-to-149-seat planes, and has marketed the CSeries plane as being 20 percent more fuel-efficient than the comparable Airbus A320 and Boeing 737 family of aircraft. The CSeries is critical to Bombardier Aerospace, which has spent years designing the advanced-technology jet.

Originally scheduled for commercial delivery in late 2012, the CSeries is Quebec-based Bombardier's ambitious narrow-bodied, twin-engine medium range jet model, tailored toward a growing market of business travellers.

The company began its first real-life flight tests for the prototypes last fall, and is trying to convince airlines to transfer their aging fleets.

Analyst David Tyerman of Canaccord Genuity said the news wasn't good for a program that has already endured a series of delays, but the impact will depend on the seriousness of what occurred.

Tyerman said the incident could delay the certification and will probably further postpone orders, which have been weak as potential customers await flight data from the four test aircraft produced so far.

Bombardier shares shed almost four per cent to trade at $3.68 on the TSX on Friday.

With files from Canadian Press