Hopes that US would now cough up £3.5m in unpaid charges and fines dashed

Hopes by Boris Johnson that Barack Obama's new ambassador in London would pay almost £3.5m in unpaid congestion charges and fines run up by the previous administration were dashed today as the new regime confirmed it has no intention of settling the bill.

A spokesperson for the mayor of London said that Johnson, who is on holiday, was disappointed that the US embassy was choosing to "continue to ignore" its responsibility to Londoners by paying the £8 daily charge incurred by those driving within the city's congestion charge zone, as well as fines built up for non-payment.

The mayor had hoped that Obama's new representative in London, Louis Susman, who was sworn in two weeks ago and arrived in the capital today, would signal a change of approach due to the new administration's green credentials.

But a spokesman for the US embassy confirmed that Washington's position had not changed.

In total, Transport for London says the embassy now owes a backlog of charges and fines worth £3,446,420.

Around a quarter of embassies share the US view that they are exempt from the charge because it is a tax, and therefore not payable because of their diplomatic immunity.

The US embassy spokesman said: "Our policy on the congestion tax is a long-standing policy decided on by Washington. The US government's position is that this a tax and therefore is prohibited by various treaties."

The disclosure will intensify the battle between Transport for London and foreign embassies who refuse to pay the charge and collectively owe around £28m.

Last year, the mayor made clear his fury at diplomats based in London who refuse to pay for driving in the congestion charge zone.

At a public meeting in November, Johnson claimed he would happily "slap on asbo" on non-paying embassies were it not for the Geneva conventions.

A spokesman for Johnson said today that the change in ambassador had been the "perfect opportunity" to resolve the dispute.

"The mayor is deeply disappointed that it seems they may not choose to do so. The congestion charge is a service, not a tax, which is paid by the majority of embassies and millions of Londoners. There is simply no excuse for the American embassy to continue to ignore this responsibility to its host city and the mayor will continue to press this point to their representatives."

A TfL spokeswoman pointed out that three quarters of embassies pay their dues.

"TfL and the UK government are agreed that the congestion charge is a charge for a service and not a tax, which means that diplomats are not exempt from payment. All staff at the American embassy should pay it, in the same way as British officials pay road tolls in the United States. TfL continues to engage directly with those embassies that refuse to pay in order to increase compliance with the scheme by diplomats."