A businessman today told how he was branded a terrorist by US immigration officials, questioned for 28 hours and then expelled from the country.

Kamran Hussain, 32, was detained when he flew into Los Angeles airport for a business conference, handcuffed and placed in a cell.

"The first hour or so it was OK, but when it went on for three or four hours I thought something wasn't right," he said. "Once they started asking me terrorist-related questions it got me worried.

"I kept thinking when would it end and why were they asking me these questions?"

Mr Hussain, formerly of Bradford, who now works as an IT director for a London law firm, claimed he was told that a letter had been sent to the US Embassy in London alleging he was going to America to conduct terrorist activities. "I was left speechless for a few minutes, completely in shock," he said.

"I then replied that this was a complete joke, I have never been involved in any form of terrorism and do not support any form of terrorism."

Mr Hussain fears the incident could jeopardise future business trips abroad.

"They've written on my passport that I was refused entry into the US."

Vincent Cable, Liberal Democrat MP for Twicken-ham, where Mr Hussain now lives, is writing to Foreign Secretary Jack Straw.

"I want the Home Secretary to obtain this alleged incriminating letter that was never shown to Mr Hussain and probably never existed. But if it does exist it needs sending to us for investigation," Mr Cable said.

Mr Hussain's brother Imran, 35, of Thornton, Bradford, said Kamran called him as soon as he landed back in England.

"We were completely shocked," he said.

"It's not that he hasn't travelled before he went to the States and he has no police record."

The American Embassy refused to comment on individual cases, but its website stated that immigration authorities applied "discretionary criteria" to people entering the country.