The Chicoutimi, an Upholder/Victoria-class submarine like its counterparts the Victoria, Windsor and Cornerbrook, is diesel-electric-propelled.

Britain sold the four off to Canada in a 1998 deal when London opted for a entirely nuclear-powered fleet, and have replaced Ottawa's three Oberon-class submarines which were in service for more than 30 years.

The Canadian navy has hailed the stealth and silence of the 70-meter (230-foot), 2,150-tonne submarine, saying it is difficult to detect and useful for conducting surveillance and intelligence-gathering.

The Chicoutimi, built in 1983 by Vickers Shipbuilding and Engineering, in Barrow-in-Furness, northwest England, can travel without refueling for up to 14,400 kilometers (8,950 miles), at a speed of eight knots (roughly 14.5 kilometers per hour).

With a standard crew of about 50, it is armed with Gould forward Mark 48 torpedos that are effective for hundreds of kilometers, according to Jane's Fighting Ships reference book.

The four Victoria-class subs were purchased from Britain for 750 million Canadian dollars (595 million US dollars, 483 million euros, in current rates).

But criticism of the purchase began in 2002, when a dent was discovered in the first delivery, the HMCS Victoria.

Exhaust valves were also found to be faulty on all four ships, which led to a massive leak in 2002 on a training exercise of the HMCS Windsor.

The Chicoutimi was only formally handed over to the Canadian navy on Saturday, in a formal renaming ceremony at Britain's Faslane submarine base in Scotland.

It was on its way to Halifax, in the eastern Canadian province of Nova Scotia, when the fire broke out Tuesday.

A major rescue operation by Britain's Royal Navy and Air Force was under way, with helicopters and ships including a frigate dispatched to the submarine, located some 100 nautical miles (180 kilometers) northwest of Ireland.

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