TORONTO (Reuters) - Canada's WestJet WJA.TO said on Tuesday it has selected Bombardier Inc BBDb.TO to supply aircraft for its new regional airline, expected to launch in the second half of 2013.

Calgary, Alberta-based WestJet said it has signed a letter of intent to buy 20 Q400s with the option to purchase an additional 25 aircraft.

The airline plans to fly Bombardier’s Q400 NextGen to cities and existing destinations not currently connected by WestJet.

WestJet said its plan will allow it to improve schedules on certain routes where a smaller aircraft can efficiently provide greater frequency. The airline expects to announce its initial regional schedule using the Q400s later in 2012.