The incident took place when Mr Hughes was approached by a Turkish former illegal immigrant and his relative after putting out the appeal.

Defending QC Jonathan Goldberg claimed the Turkish men had "haggled" for their evidence in order to get permanent immigration status for the older man and a business loan with the help of Mr Hughes.

Putty in their hands

Mr Goldberg said: "Mr Simon Hughes, God bless him, must have been putty in the hands of these two.

"That nice, proper, affable Englishman had wanted to do the best for his constituents, the police and the public to encourage witnesses to come forward in this horrible murder," but he said, "he was conned."

Mr Goldberg was making his final speech in the trial of five youths who have denied murdering 17-year-old Jamie Robe who was beaten to death near the Osprey Estate, Rotherhithe, east London, early on 7 August 1997.

Witnesses who came to court to give evidence for the prosecution during the trial included an illegal immigrant from Turkey and his nephew.

Forged passport

Mr Goldberg said the illegal immigrant had earlier equipped himself with an "excellent" forged Dutch passport to present to the Home Office to get employment cards.

Then there "suddenly comes an opportunity - laced with a daily newspaper's offer of a handsome reward - to cure the illegality".

"It can be cured overnight and Simon Hughes says he will use all his best efforts."

Mr Goldberg said Mr Hughes "could not have known of the false passport".

'Brilliant con'

"The Home Office, the police - none of them knew about this until we learnt about it by a slip of the tongue in this court for the first time.

"This was a successful con, a brilliant con. They have haggled for their evidence. They went to see Simon Hughes in February and he made them all these liberal promises.

"They did not make witness statements until June. Even then they say they are not coming to court to back up their statements unless that leave [to remain in the UK] arrives."

The Home Office immigration service wrote to the police in April saying "no go" over granting permanent immigration status.

But Mr Hughes had two meetings with Home Office minister Mike O'Brien in August and September and had persuaded him to overrule his own civil servants.

Fear of reprisals

Mr Goldberg said: "What they have done is a con of wonderful proportions. They have got away with it. The question is whether you will also be conned or have the scales removed from your eyes at what has gone on."

Earlier in the trial he had accused the immigrant's nephew of selling his evidence so his uncle could remain in the UK.

The 30-year-old man, who gave evidence from behind screens because he fears reprisals, denied the claim.

He said he had seen Jamie kicked and beaten to death.

The trial was adjourned until Thursday.