An overwhelming majority of businesses oppose plans to extend the present congestion charge zone, according to the latest survey by the London Chamber of Commerce and Industry.

The results come from the quarterly London Monitor, which is a regular business confidence survey taken of a statistically balanced cross-section of firms in the capital.

This shows that 67.1 per cent of businesses are opposed to the extension and only 19 per cent in favour. 13.9 per cent are currently undecided.

The heaviest opposition is to be found in the retail sector - 74.2 per cent are against an extension and 19.4 per cent in favour. Separate London Chamber reports on the impact of c-charging on retailers during the last year have found that the £5-a-day charge is widely blamed for a downturn in takings.

But other sectors, too, are also clearly opposed to an expanded c-zone. Only 14.9 per cent of the finance sector supports the extension compared with the 68.7 per cent which opposes it; in this sector, a higher 16.4 per cent are undecided.

Broken down by business size, big employers are heavily against. In the 500+ employee category, 75 per cent oppose extension with 20.8 per cent in favour. In the smallest 1-19 category, 68.5 per cent oppose the proposal with 16.1 per cent in favour.

The results are particularly significant because London Monitor surveys carried out before the charge was implemented 13 months ago, based on a similar sample, consistently showed a majority in favour of the congestion charge.

This strongly suggests a significant shift in business opinion over the last 15-18 months. No studies have yet been made of what has caused the change, but it seems reasonable to assume that a major factor must be experience of the impact of the scheme.

Piers Merchant, campaigns director of London Chamber, said: "Any extension of congestion charging in its present form would be damaging for many businesses."

"We want to see the congestion charging experiment work. But at present, that plainly isn't happening. It is therefore unsurprising that business has turned against the scheme."