Having described the US Ambassador to England, Robert Tuttle as a ‘car salesman’ and a ‘chiselling little crook’, London’s Mayor is looking at ways to chase the outstanding £400,000 owed to his office for unpaid congestion charge fees.

The US Embassy, along with some 55 other countries are disputing London’s congestion charge, claiming that the charge is a tax rather than a levy, which foreign diplomats are not required to pay under the 1961 Vienna Convention. The US is thought to be running up around 300 unpaid congestion charge fines per month.

In July 2005 the congestion charge was increased from £5 per day to £8 per day for vehicles entering central London. From February 2007 the zone will be extended westwards to cover parts of Kensington and Chelsea.