OTTAWA -- Two locomotives fronting a westbound Canadian Pacific freight train left the tracks in Smiths Falls early yesterday, sending 12,000 litres of diesel fuel seeping into the city's sewage system, the Ottawa Citizen reports.

The accident occurred while the train was still inside the city's railyards, and while Canadian Pacific emergency crews raced to clean up the spill, emergency officials with the city cautioned nearby residents to check for an odour of diesel fuel in their basements.

"There is very little risk of any explosion or fire," said Aire Hoogenboom, emergency information director for Smiths Falls. "Other than the odour, there should be no danger.

"There is no threat to the city's water system and only those residents who operate off their own wells should check for any signs of fuel seeping into their well."

The train had just left the yards about 1:15 a.m., bound for southwestern Ontario when the mishap occurred, no more than a few hundred metres from where the train began.

CP officials said the train originated in Montreal late Sunday and arrived in Smiths Falls late at night for a brief stopover and crew change.

At the point the locomotives jumped the track, the train was travelling about 15 km/h. "The cause remains under investigation and we can't determine the exact cause until the locomotives are moved back onto the track and out of the way," said CP spokesman Mike Spinard.

Both locomotives remained upright, but a fuel tank on the lead locomotive was punctured by the force of the derailment, allowing the fuel to spill.

Fire department personnel contained the fuel as quickly as they could while emergency officials determined what route the rest of the fuel might take and made preparations to clean up the remainder.

Officials reported up to two dozen complaints about the odour of diesel fuel. There were also signs that fuel had seeped to the city sewage filtration plant and arrangements were being made to siphon it off.

The cleanup was expected to be completed today, and the track cleared by this morning.