Olympic VIPs are to be provided with a designated lane on the North Circular Road during the London 2012 Games, bringing chaos to the already congested route, it was warned this week.

For up to 60 days during the Olympics and Paralympics, one lane of the A406, in both directions, is likely to be condoned off, so that athletes, officials and dignitaries can get to events on time.

This plan will reduce the A406 to just one lane around Bounds Green, a proposal Barnet Council has branded 'impracticable'.

These, and other, 'grave concerns' were raised by the council in a report published by Parliament's Transport Committee this week.

"We are concerned that this will not only exacerbate the existing problem, but by 2012, the growth in traffic may make this option impracticable, especially as in some sections, the A406 would be reduced to a single lane for general traffic," a submission by the council reads. "In addition to the congestion, pollution and accidents which occur on the A406 itself, adjacent borough roads are plagued by rat-running traffic using parallel routes to avoid the worst sections of the A406."

Motorists straying into the Olympic lane will be fined up to £5,000 if they decide to take the fast route, thanks to legislative powers provided by the London Olympics Bill, and the lanes are likely to be enforced with cameras and patrols.

Plans to improve the North Circular worth £600 million were dropped last year for a much smaller scheme at the Bounds Green bottleneck. This plan has now been delayed, and is to be reviewed, but even if this minor scheme gets the go-ahead, many traffic experts, including Transport for London's own consultants, believe the move could worsen congestion in the long term.

Councillor Brian Coleman, Barnet and Camden representative on the London Assembly, believes that the cocktail of Transport for London (TfL) inaction, the growing number of cars on the road and the introduction of the VIP lane will cause mayhem during the Games. "The residents of north London will feel cheated and rightly so," he said. "This is crazy, I suggest people go on holiday, because it will just be chaos."

But a spokesman for TfL backed the proposal and said that everything would be done to ensure that Londoners would not be inconvenienced. "It is absolutely essential London has to get its athletes and officials to venues on time."