An airline passenger barred from a flight for wearing a T-shirt labeling President Bush a terrorist has threatened legal action against Australia's flag carrier Qantas.

Allen Jasson, 55, an Australian IT expert who lives in Britain, was stopped from boarding a London-bound Qantas flight at Melbourne Airport on January 19 for wearing what the airline said was an offensive T-shirt.

Airline staff said the T-shirt of Bush with the tagline "World's number 1 terrorist" could have upset other passengers and demanded it be changed for another.

But Jasson, who had earlier traveled on a Qantas domestic flight wearing the Bush T-shirt, said his right to freedom of speech had been infringed by Qantas.

"I am not prepared to go without the T-shirt. I might forfeit the fare, but I have made up my mind that I would rather stand up for the principle of free speech," Jasson told Australian media on January 22, adding he would seek legal advice.

Qantas issued a statement saying comments made verbally or on a T-shirt which had the potential to offend other travelers or threaten the security of aircraft "will not be tolerated."