MONTREAL - Air Canada has joined rival WestJet Airlines in charging a $25 fee for first checked bags on domestic flights.

The fee applies to passengers booking the lowest economy class Tango fares, as of Thursday for flights as of Nov. 2.

The Montreal-based airline (TSX:AC.B) already charges first checked bag fees for U.S. transborder routes and will now add a fee for flights between Canada and the Caribbean and Mexico.

Earlier this week, Calgary-based WestJet announced a first checked baggage fee, which ranges between $25 and $29.50 depending on provincial taxes, for flights within Canada and to the United States, but not to Mexico, the Caribbean, Central America and Europe.

Industry observers had expected Air Canada to add the fee, which it says will affect about 20 per cent of passengers on domestic flights or about five per cent of its global traffic.

The fee doesn't apply to other economy class and business fares, loyalty members or customers purchasing Air Canada Vacations packages