The prosecution in the case of Jean Charles de Menzes allege manipulation of evidence by the Metropolitan police

A composite image comparing Jean Charles de Menezes and Hussain Osman, one of the 21/7 plotters, shown to a jury by lawyers for the Metropolitan Police was dishonestly manipulated, it was claimed today.

The picture, containing half the face of innocent Brazilian Mr de Menezes and half the face of terrorist Osman was produced at the force's Old Bailey trial.

It was claimed to illustrate the difficulties officers would have had in differentiating the two.

But Clare Montgomery QC, prosecuting, told the court that it had been altered "by either stretching or resizing so the face ceases to have its correct proportions".

The judge, Mr Justice Henriques, told the jury: "A serious allegation has been made that a picture has been manipulated so as to mislead."

Police are accused of a "catastrophic" series errors leading to the shooting of Mr de Menezes, 27, on July 22 2005, after he was mistaken for Osman.

Today a forensics consultant, Michael George, told the court that the composite could not have been produced using Powerpoint software, and appeared to have a "greater definition" than the two used to produce it.

He produced an alternative composite, shown to the jury, in which the two faces have different skin tones and their mouths and noses are not aligned.

Earlier, the judge challenged Mr Thwaites over his line of questioning over Mr de Menezes's immigration status.

Mr Thwaites cross-examined an immigration official, Paul Roach, over a counterfeit stamp found in the Brazilian's passport, asking if this meant he would have been in the country illegally.

But the judge later told him: "He is a member of the public who is entitled to the protection of the Health and Safety at Work Act whatever his status, is he not?"

"I don't think that is relevant," said Mr Thwaites.

"I wondered what the inquiry was about," said the judge.

"I'll make it clear in due course," replied Mr Thwaites.

Mr Roach had told the court the Brazilian first entered the country on March 13 2002 and was given six months' leave to remain, before extending his stay, as a student, to June 30 2003.

The next record of him was that he arrived in Ireland from France on April 23 2005 but there was no record of when he then came to the UK.

As a person entering Britain from Ireland he would have had an automatic three-month leave to remain which at the earliest would have run out on July 23 2003, the day after he was killed, the court heard.

A counterfeit stamp found on his passport may only have been added after he entered the UK, Mr Roach said.

The prosecution closed its case and the trial was adjourned until tomorrow.