The eighties pop icon Boy George has been told to expect a prison sentence after being found guilty of falsely imprisoning a male escort.

The former Culture Club singer handcuffed the Norwegian Audun Carlsen to a wall before beating him with a metal chain when he tried to escape after a naked photo shoot.

The 47-year-old – appearing at court under his real name, George O'Dowd – did not give evidence during the trial, but the court heard that he told police that he had handcuffed Mr Carlsen to a bed in his flat in Shoreditch, east London, because he thought the escort was tampering with his computer.

But Mr Carlsen offered the court a different explanation, telling the jury that O'Dowd had concocted the story about the computer, and that the real reason for the attack was the victim's refusal to have sex with the star. Mr Carlsen, 29, said: "I think he couldn't handle the refusal – me not having sex with him."

Following the jury's verdict, Judge David Rutherford, at Snaresbrook Crown Court, granted O'Dowd bail ahead of sentencing on 16 January, but warned the singer: "This is a case where custody is the more likely option. The fact that your bail is being continued does not imply that this will be dealt with by a non-custodial sentence. I don't want any false expectations created."

The judge was told O'Dowd had previous convictions for going equipped for theft as a juvenile in 1977, and a Class B drugs matter 10 years later. There was also an incident in New York recently that was, in effect, wasting police time. O'Dowd left the court without speaking to reporters.

The court heard that O'Dowd and Mr Carlsen had met through the Gaydar website – a social networking site for gay and bisexual men. They arranged a meeting at O'Dowd's flat and, the prosecuting barrister, Heather Norton, told the court, that meeting was going well until the singer suspected Mr Carlsen had hacked into his computer. Despite that, they parted on good terms and O'Dowd paid the escort £300 of the £400 they had agreed.

In the weeks that followed, the pair exchanged emails in which O'Dowd accused Mr Carlsen of hacking into his computer. But in later emails the singer expressed his wish to see the younger man "naked asap" – in particular his "heavenly butt". They agreed to meet a second time three months later.

But it was at the second meeting that Mr Carlsen was set upon. He told the court that, after being called into O'Dowd's bedroom, he was leapt on by the singer and another man who wrestled him to the floor and started beating him. He said that during the attack, O'Dowd was screaming "Fucking whore! Now you're going to get what you deserve." Afterwards he was dragged to the bed where he was handcuffed to a hook in the wall. Then Mr O'Dowd produced a plastic box containing chains, sex toys and leather straps.

However, the Norwegian managed to pull the hook out of the wall and ran to the door with O'Dowd pursuing him, lashing him with a metal chain. Mr Carlsen escaped the flat and ran into the street in his underwear and screamed for help.

When arrested, O'Dowd told the police that he believed Mr Carlsen had stolen naked photographs of himself from his laptop and in doing so had "messed up" the computer. He said that the suggestion his motive was because Mr Carlsen had refused to have sex with him was "entire fantasy or a lie". He denied punching or assaulting the Norwegian and claimed that the bruises he sustained could have been because the escort is HIV-positive.

During a police interview, O'Dowd told officers: "I asked him to come [back to my flat] because I wanted to find out if this guy had borrowed my stuff. I got a friend there because I wanted to make sure he didn't leave so I could check the computer and his phone. The friend was just there in case he tried to stab me or take a hammer to me." He said Mr Carlsen "struggled a bit" when he was handcuffing him "because he realised I wasn't messing around". He added: "I didn't tell him the reason I was doing what I was doing. I said I just wanted to check something. He was saying 'Let me go'."

He denied to police that he had called Mr Carlsen a whore, saying: "My boyfriend is an escort. Why would I call him a whore?"