It's the hidden cost in Canada's fight against terror: long johns geared for chemical warfare.

The Canadian Forces are looking to replenish depleted stocks of long underwear at its Counter Terrorism Technology Centre in Alberta.

Ottawa has posted a public tender seeking 1,500 sets of undergarments -- tops and bottoms -- that will be worn under protective suits by personnel during chemical-warfare training exercises.

The government requires the clothing to be colour co-ordinated according to size, able to wick moisture away from the body and durable enough to withstand multiple launderings.

The tender says the fresh underwear must be delivered by March 31.

The posting does not specify how much money has been set aside for the purchase.