TORONTO - Porter Airlines is increasing its service to Washington Dulles International Airport, with a fourth daily flight from Toronto as of May 15, the airline said Monday.

Service to the Washington, B.C.,-area airport begins on April 16 with three daily round-trip flights from Billy Bishop Toronto City Airport.

"We are adding an additional daily flight to accommodate demand and provide a more convenient schedule for our passengers," Porter president and CEO Robert Deluce said in a news release.

It will be the sixth U.S. destination for the Canadian carrier.