Airline staff argued the T-shirt, which bears an image of the US President with the slogan "World's number 1 terrorist", was a security risk or an item likely to upset passengers. The airline earlier prevented him from flying to Melbourne for Christmas with relatives on December 2 until he removed the shirt.

Domestic carrier Virgin Blue took the same action when Mr Jasson tried to catch a connecting flight to Adelaide, but on a return flight to Melbourne with Qantas on Friday, he successfully wore the shirt. Mr Jasson said he cleared international security checks and arrived at the departure lounge in Melbourne for the flight home when he approached the gate manager, congratulated him over Qantas allowing him to wear the shirt and demanded an apology for his earlier treatment. "I concede that I raised the issue, but I wanted primarily to thank Qantas for relenting when [the gate manager] told me: 'I'm surprised you got this far, the staff should have stopped you,' " Mr Jasson said.

Mr Jasson said he risked missing his chance of permanent residency if he spent more than two months out of Britain. But the Adelaide-born former Melbourne resident said he was seeking legal advice to challenge the airline's policy and recover costs.

"To be fair to Qantas, they have said I can take another flight if I don't wear the T-shirt but I am not prepared to go without the T-shirt," he said. "I might forfeit the [$2500] fare but I have made up my mind that I would rather stand up for the principle of free speech." When asked whether the stand was worthwhile, Mr Jasson said: "In Australia today it is very sad that that question has to be asked.

"It's very sad that I find that question has to be asked in Australia. It's a very unhealthy situation and it makes me feel very sad. "It's one of the reasons that I now live in the UK."

Reading from a prepared statement, a Qantas spokesman said: "Whether made verbally or on a T-shirt, comments with the potential to offend other customers or threaten the security of a Qantas group aircraft will not be tolerated." AAP