London mayor Boris Johnson is to ask Londoners whether the city's western extension congestion charging zone should remain or be overhauled.

Mr Johnson has announced that a five-week public consultation on the future of the zone will begin in early September.

The mayor said he was "particularly keen" to garner the opinion of local residents, retailers and businesses within or on the borders of the extension.

He said: "The western extension is a massive issue for those that live and work in the west of our city and the consultation is likely to elicit strong views.

"I am going into this with an open mind and this will be a genuine consultation. Londoners can be assured that, whether they stand for or against, this time their opinions will be respected and we will abide by the results."

Mr Johnson maintained the consultation was "not a referendum" with the public restricted to simply voting for or against the zone.

He added: "This will be an opportunity for everyone with experience of the extension to tell me whether they want to see it removed, improved or if they are simply unmoved."

The congestion charge was introduced in 2003 and extended westwards to cover most of the boroughs of Kensington & Chelsea and Westminster in February last year.

A London Assembly Conservative party spokesman welcomed the consultation. He said: "Ken Livingstone forced through the Western Extension despite the fact that Transport for London's consultation showed that 62 per cent of residents were opposed to it.

"There are strong economic and environmental arguments against the Western Extension and I would expect to find that a majority of the public is in favour of its removal."

Information on the consultation and the options will be made available on the TfL website.