Sir Ian has been forced to defend his actions and comments

Peter Smyth, of the Metropolitan Police Constables Board which represents 24,000 of the force's officers, said it had "no confidence" in Sir Ian.

He then compared civilian community support officers (CSOs) to "gaggles of lost shoppers".

Sir Ian said his claims did not reflect the views of hundreds of officers.

In an open letter, Sir Ian said he was "gravely disappointed" Mr Smyth had chosen to portray a crisis of confidence in his leadership.

Valued individuals

The attack on CSOs had been carried out in "emotive and frankly disgraceful language", he added.

"These CSOs are your colleagues. Some of them have saved your members from injury.

"They are members of the Met team, they are valued individuals in their own right and you have no right to attack them in public in that way."

He cited improved arrest and detection rates, falling crime, lower sickness absence and a queue of people who wanted to join the force as a success of his leadership.

He also suggested any concerns should have been made in private.

There is a deepening discontent within my organisation Peter Smyth

Mr Smyth said a series of "embarrassing gaffes" by Sir Ian had undermined the force.

His comments were made at a Police Federation annual conference, attended by new police minister Liam Byrne.

He told the conference in Bournemouth: "On behalf of the 24,000 constables in London, and at the request of my branch board, I am telling you that we have no confidence in this commissioner."

Sir Ian has hit the headlines in recent months in a row over secretly-taped telephone calls with ministers, comments about the Soham murders and remarks about the police shooting of innocent Brazilian Jean Charles de Menezes.

Speaking later to BBC London, Mr Smyth said there were concerns police would be based in call centres while the streets would be patrolled by community support officers.

"We say that is wrong. We want police officers on the street, out in the community where people need them.

"There is a deepening discontent within my organisation and quite evidently among the wider public. We felt we could no longer stay silent on this issue."