Mayor of London Ken Livingstone's proposed improvements to the North Circular Road were called into question this week by a report which branded an almost identical scheme as having no benefit to either consumer or business users.

The 2004 Hyder report, which was commissioned by Transport for London (TfL) and released under the Freedom of Information Act this week, claims that planned improvements to the North Circular around Bounds Green will not improve congestion, and that jams will eventually worsen on the stretch as traffic increases.

The revelation came as TfL unveiled the final details of its Bounds Green scheme on Wednesday, and now brings into question the Mayor's claims that the scheme will reduce rat-running through Muswell Hill.

The Hyder paper, which cost TfL £83,000, also says that the best value for money would be provided by a scheme shelved by the Mayor which would have included the road being widened to six lanes between Wilma Way and Green Lanes in Haringey.

"The Bounds Green scheme is a sticking plaster solution," said Lynne Featherstone, the Liberal Democrat MP for Hornsey & Wood Green, who believes a six-lane expansion is vital to reduce traffic in Muswell Hill and Alexandra Palace.

"The Mayor has decided that he does not wish to borrow, and he cannot seem to get the funding out of the Government," she said. "He should place a priority on the North Circular it has been a problem for years."

Another TfL-commissioned report, compiled by Faber Maunsell in 2003 for £11,000, concluded that the smaller Bounds Green scheme would not improve congestion, would make rat-running worse and make no major contribution to London's economic regeneration or development.

The report went on to say that without the major schemes, this section of the North Circular would remain a weak link and the unsatisfactory situation between Bounds Green and Green Lanes will gradually worsen'.

The Hyder report said the six-lane solution was the only option to provide a return on the investment. But in September last year, Mr Livingstone announced that the £600 m road-widening scheme was not cost-effective, while the small Bounds Green scheme would be brought forward. Question marks have also been raised over TfL's cost and benefit figures.

Barnet Council, which along with Enfield and Haringey councils, has fought for the major schemes, said this week that it was baffled with some of the numbers used to justify the adoption of the scheme.

But a spokesman for TfL said its methods were correct. "The subsequent settlement with the Treasury, though substantial, did not fund every project proposed by TfL and this included the inherited schemes for the A406 North Circular Road," he said.

The proposals at Bounds Green include road-widening to two lanes and junction improvements. TfL will hold a public exhibition on the scheme from next Thursday to Tuesday, June 14, at the Trinity-at-Bowes Methodist Church, Palmerston Road, Palmers Green.