The film dramatises events on a flight which crashed in when passengers fought back against hijackers.

The President watched the film with his wife, Laura, and relatives of the some of the people who died on the flight.

United 93 has earned almost $30m (�16m) at the US box office and will be released in the UK this weekend.

"The President has always said that those who were on the flight, that the passengers and crew members of the flight were heroes," said White House spokeswoman Dana Perino before the screening.

The film was made by British director Paul Greengrass, who had approval from the relatives of the individuals who died on United 93.

David Beamer, whose son Todd is believed to have led the counter-attack against the terrorists on the flight, has spoken of the film's emotional impact.

"You come out of that movie, and the first thing you've got to do is - if you haven't told a loved one you love them lately, then give them a hug.

"Because we don't know when our last opportunity is to do these good things."