CALGARY - Thousands of Swoop passengers have been forced to make alternative last-minute flight plans after the WestJet Airlines (WJA.TO) discount subsidiary cancelled 16 flights in the coming days between Canada and the United States.

Flights have been cancelled between Abbotsbord, B.C., and Las Vegas, and between Hamilton, Ont., and Las Vegas, Orlando, Tampa and Fort Lauderdale, according to its website.

Swoop says it hasn't received a final approval required to operate to the United States that it had anticipated having well in advance of the first flights.

The airline that launched service in Canada in June apologized for the inconvenience the cancellations have caused.

It says employees are directly contacting travellers to offer rebooking options or full refunds.

It has leased an aircraft to operate flights between Edmonton and Las Vegas scheduled to depart Friday and Oct. 26.