London’s mayor on Monday accused the US ambassador to the UK of behaving “like a chiselling little crook” in a spat over the embassy’s refusal to pay the city’s road toll.

Ken Livingstone, the famously outspoken left-wing mayor and long-standing critic of American foreign policy, delivered his latest outburst during a television interview. His assault on Robert Tuttle was prompted by the long-running dispute over the embassy’s refusal to pay the congestion charge, a toll that is levied on those driving through central London during business hours.