Embassies in London have unpaid fines of at least £20,000 a day in the new western extension of the congestion charge zone, research has suggested.
The congestion charge area includes almost 150 embassies
In the eight days after the 21 February change, fines for embassies exceeded £150,000, the Liberal Democrats said.
The fines included more than £39,000 for the Russian embassy and nearly £25,000 for the German office.
Several nations stopped paying the £8 charge after the extension, saying it is a tax from which they are exempt.
Total fines for congestion charges owed by all embassies - mostly those outside the western extension - were close to £8m on 21 March, the Lib Dems said.
They are protected from enforcement by diplomatic immunity.
"This is an insult to law-abiding London taxpayers," said Geoff Pope, Lib Dem Transport spokesman on the London Assembly, of the latest figures.
He said all embassies should pay the charge as it helps fund improvements to the city's transport network.
"If 42 embassies in the western extension can settle up without any trouble, it gives the lie to the claim of others that London's congestion charge is a tax not a toll - their fig leaf excuse for not paying it," said Mr Pope.
The Russian embassy said it had suspended payments on 19 February, as it was "contradictory" to the Vienna Convention on Diplomatic Relations.
London Mayor Ken Livingstone said his office had taken "endless legal advice", but could not find any way around the rules that say "diplomats aren't subject to the taxes and laws of other countries".
The expanded congestion charge zone, which now takes in Kensington and Chelsea, includes nearly 150 embassies.
In February, the embassies of France, Germany, Belgium, Slovakia and Belarus all confirmed to the BBC News website that they had suspended payments.
Following the decision, the office of the Mayor of London said: "Those embassies that flout the law of this country and misuse diplomatic immunity to avoid the charge are enjoying the benefits of reduced congestion but contributing nothing."