Continental Airlines canceled a Sunday evening flight from Washington to Houston after security concerns were raised by the Homeland Security Department.
Department spokesman Brian Roehrkasse said Flight 1519 was canceled "due to security concerns and threat reporting about that particular flight."
He added that the federal agency and Continental "worked closely on the matter," but did not give any further details of the threat.
The cancellation came on the heels of announcements Saturday that six international flights scheduled for Sunday and Monday were canceled because of security concerns.
In Houston, Continental spokesman David Messing said the Sunday domestic flight was canceled "because we were unable to get security clearance from the Department of Homeland Security."
Messing said he did not know what security concerns the agency had and that passengers were being booked on other flights.
The flight was scheduled to take off from Dulles International Airport outside Washington at 5:45 p.m. EST and arrive at Bush Intercontinental Airport at 8:10 p.m. CST.
The National Football League's Super Bowl was being played Sunday evening at Reliant Stadium, approximately 27 miles from the airport.
However, a U.S. government official said the flight cancellation was not specifically connected to the Super Bowl.
A Continental Airlines flight Sunday from Glasgow, Scotland, to Los Angeles with an intermediate stop in Newark, N.J., was canceled late Saturday because of security concerns, but there was no indication whether that was related to the Washington-Houston cancellation announced late Sunday.
The Scotland-Los Angeles flight was one of six U.S.-bound flight cancellations for Sunday and Monday announced Saturday because of security concerns. The U.S. government said it had fresh indications of al-Qaida's continued interest in targeting commercial planes flying to the United States.
British Airways canceled Flight 223 from London to Dulles for Sunday and Monday and Flight 207 from London to Miami on Sunday. Air France Flight 026 from Paris to Washington on Sunday and Monday.
Return flights in all five instances also were canceled, because aircraft would not be available for the return trip.