The worst traffic hotspot in the UK is on the western section of the M25 orbital motorway around London, according to a new report.

Figures soon to be released by the road information specialist, Trafficmaster, show the section between the A3 in Surrey and the M1 near Watford, Hertfordshire, is the most congested.

The report says the 10 worst motorway "hotspots" for jams have all seen large increases in traffic over the last five years.

It coincides with a government announcement that �145m is to be spent on combating congestion.

Secretary of state, I have to tell you that your customers are complaining - the current product just won't do

Richard Turner, Freight Transport Association

Trafficmaster defines congestion as the amount of time spent in traffic travelling at less than 30mph on roads where the limit is 70mph.

It says jams have increased by at least a third in the worst areas since 1998 and road use overall rose by 1.3% in the last year.

On Wednesday Transport Secretary Alistair Darling is to give the go-ahead for �145m of engineering work which he says will improve the situation for millions of motorway users.

The projects are expected to involve minor design changes to junctions to improve traffic flow rather that major construction schemes.

But the Freight Transport Association (FTA) has attacked the government over the road and rail infrastructure.

At a dinner attended by Mr Darling, FTA chief executive Richard Turner said the government had to tackle congestion.

Industry costs

He said high fuel taxes meant that FTA members, as customers of road and rail, were paying a high price for an "unreliable and unacceptable" project.

"Secretary of state, I have to tell you that your customers are complaining. The current product just won't do," he said.

He said that congestion was costing British industry �20bn a year, which was more than the government was spending each year in its 10-year transport plan.

Mr Darling replied that the government was committed to substantial improvements over the next 10 years.

"There will be 100 junction improvements delivered by next spring... and I will announce the go-ahead for �145m package for more junction improvements - many at pinch points you have told us cause you problems."