Pc Christopher Exley, who served in the Special Operations Division which includes the Royal and Diplomatic Protection squads, the Flying Squad, Special Branch and the Counter Terrorism Command, was allegedly caught in an undercover sting on December 5 last year.

It is claimed he told the boy, who was in fact another police officer, that he would like to have a 'naked coffee' with him.

Police also found 53 indecent images of children on his home computer after he was arrested on February 3 this year.

Dressed in a dark suit, white shirt, and navy tie, Exley spoke only to confirm his name and enter not guilty pleas to five charges when he appeared at Southwark Crown Court.

He denied attempting to 'arrange or facilitate an act which would involve the commission of a sexual act, namely engaging in a sexual activity with a child'.

Exley also denied four other counts relating to the images found on his computer, including a number of pictures at the second highest level of severity.

His barrister Robert Morris asked for a fixed trial date saying: "In relation to the images this is a case where expert evidence is going to be required on both sides".

Judge Nicholas Loraine-Smith set the trial for December 10. It is expected to last three days,

Exley, of Clapton, east London, denies attempting to arrange or facilitate a child sexual offence, three counts of making indecent images of children, and one count of possessing indecent photographs of a child.

He was remanded on bail on the condition he does not have contact with any child under the age of 16 ahead of his next appearance at the same court for trial.