(Reuters) - A Canadian soldier was killed on Friday in a friendly fire incident in Iraq, Canada's defense department said on Saturday, in the first fatality for the country during its current military mission there.

Three other Canadian soldiers were injured.

The soldiers were with Canada's special operations forces and were mistakenly engaged by Iraqi Kurdish forces following their return to an observation post behind the front lines, the defense department said in a statement.

The soldier killed was Sergeant Andrew Joseph Doiron, who had been based in Petawawa, Ontario. The three injured soldiers, who were not immediately identified, were receiving medical care.

The Canadian special forces have exchanged fire with Islamic State militants at least three times since being deployed to train Iraqi forces and also identify targets for air strikes.

Canada is due to decide in a few weeks whether to extend the six-month mandate of its military mission there.

In addition to about 70 Canadian special forces operating in Iraq's northern Kurdistan region, Canada has provided six jets to take part in U.S.-led bombing missions against Islamic State militants.

(Reporting by Jeffrey Hodgson; editing by Andrew Roche)