OTTAWA - Canada's Defence Department is in the market for some heavy, long-range artillery.

The army wants as many as 17 long-range rocket launchers to add to its stock of towed howitzers.

Public Works posted a notice Dec. 23 asking defence contractors for letters of interest, a preliminary step in the tendering process.

The notice said the system must be "fully developed and battle proven" and capable of firing precision-guided munitions.

No price tag was attached, though training, spare parts and support would be part of any potential contract.

It's unclear whether the army would require the artillery rockets in Afghanistan, where it has already deployed up to 12 new British-built M-777 howitzers.

The M-777s lob individual shells, both high-explosive and precision-guided. The rocket launchers could hit a target with as many as 12 rockets in one volley.

The British and Americans both employ rocket launchers in Afghanistan, using GPS-guided systems. The weapons, originally designed to hit enemy tank formations in the Cold War, were thought to be of little use in the hide-and-seek counter-insurgency war that Canada and its allies are waging in Afghanistan.

The head of the army, Lt.-Gen. Andrew Leslie, said in a recent interview that Canada must be prepared to fight both unconventional conflicts, such as Afghanistan, as well as old-style conventional wars, such as the conflict seen last summer between Russia and Georgia.

Leslie did not cite rocket launchers in the interview, but said the army needs to be prepared for all eventualities.

The Canadian army has wanted some form of multiple rocket launchers for years.

When Paul Martin's Liberal government asked each branch of the service in 2005 for a wish list, the army cited both M-777s and long-range rockets as necessary to re-equip the artillery branch.

Later that year, the howitzers were deemed essential for the mission in Afghanistan and the Defence Department cut a deal with the U.S. Marine Corps to buy 12 in a government-to-government purchase.

The federal government followed with a plan last year to buy as many as 34 more of the highly accurate light-weight pieces.

Senior military officials, speaking on background last year, said the plan to acquire rocket launchers was something that "would be considered much further down the road -- possibly in the 2012 time frame."

Defence industry insiders say there are only two systems on the market that would meet the Defence Department's criteria -- the M270 Multiple Launch Rocket System and the M142 High Mobility Artillery Rocket System.

The M270 is a powerful tracked vehicle that can lob 12 rockets at once between 35 and 70 kilometres.

The M142 is a lighter version, with six rocket launchers mounted on the back of a heavy wheeled vehicle.