Shortly afterwards he was held in a British jail for four months without trial, locked in a cell for up to 19 hours a day and involved in a violent confrontation with prison officers. His 'crime' was fleeing Ghana on false papers and seeking asylum in the United Kingdom.
Yesterday Mr Osei, 33, said: 'The only difference was that in England there was no physical torture. But there was mental torture. I did not know from one day to the next what was going to happen to me. I didn't know whether they would send me back to Ghana, where I would be killed. I would have killed myself if they had.'
Now free, having been granted asylum, Mr Osei says he felt shocked and cheated when he arrived in the UK. 'Nobody ever explained why I was detained. And it was almost impossible to make contact with the outside world.'
Mr Osei was studying sociology at the University of Ghana before he was forced to flee in 1989. He was one of hundreds rounded up and imprisoned for opposing President Rawlings. Some were executed. Still fearful for his safety and that of his family back in Ghana, Mr Osei is using a pseudonym.
When he arrived in London he was immediately taken into custody. At first he was held in an immigration detention centre at Harmondsworth, west London. But he was then moved to Latchmere prison in south-west London. 'It was very, very disturbing. My clothes were taken and I was given prison clothes. I was treated like a criminal and no one could tell me what was happening. I became very distrustful of authority.' A protest over conditions led to a violent confrontation with officers.
He says concern about the welfare of other immigrants and would-be refugees has made him switch his studies from sociology to law. He is about to sit his law finals.