A police officer with a severe speech impediment is still a rookie after five years.

The probationary officer, thought to have a severe stutter, has repeatedly failed passing-out exams because of his difficulty talking.

The disability means he is not allowed out patrolling the streets and cannot deal with the public.

Instead, he does admin duties at a police station in London on his full £30,000-a-year salary.

But ex-Met commander John O'Connor demanded yesterday: "Why on earth was he ever employed?

"We should seriously question whether he should be in the police. He may be a decent and intelligent person. But his physical impairment means he cannot communicate properly with the public – that means he can't operate as a police officer."

But the trainee, in his late 20s, has been given a special extension by Metropolitan Police Assistant Commissioner Tim Godwin.

Because he comes from the Caribbean, he is also entitled to extra help routinely offered by the Met to all its ethnic recruits.

Former Flying Squad boss Mr O'Connor added: "It was racist to offer him a job as a policeman in the first place. It was terribly cruel because he has no real chance of making the grade with a disability like that.

"This is political correctness gone mad and you wonder how many other trainee PCs out there cannot get through their probation.

"I have never heard of anyone being on probation for five years."

Last night the Met confirmed the rookie was still on probation and that the normal period was only two years.

A spokesman said the force had a legal obligation under the Disability Discrimination Act to make "reasonable adjustments" to help those with disabilities.