Diplomats owe more than £116m to Transport for London for unpaid congestion charges, the Foreign Office has revealed.
The US Embassy owes the largest amount at almost £12.5m, while the Embassy of Japan owes over £8.5m.
The diplomats also owe over £200,000 in unpaid parking fines, with Nigeria's High Commission owing over £47,000.
Foreign Secretary Dominic Raab said the government had held meetings with embassies to "press for payment".
But a US Embassy spokesman claimed the congestion charge was a tax which diplomats do not have to pay.
The figures for the congestion charge - the fee for most vehicles travelling in central London, which goes towards investment into public transport - dates back to between 2003 and 2018, with a total of £116,868,825 outstanding from embassies.
The parking fines date from 2018 and total £200,686.
The congestion charges for the US alone rose by more than £520,000 in one year, whilst Japan's went up by almost £500,000 for the same period.
As well as topping the list for parking fines - up by £8,000 from the previous year - Nigeria was third on the congestion charge list, owing over £7m.
In a written statement, Mr Raab said as well as the meetings, the government had written to diplomatic missions and international organisations with debts "giving them the opportunity to either pay outstanding debts, or appeal against specific fines if they considered that they had been recorded incorrectly".
However, a number of embassies claim that under the Vienna Convention on Diplomatic Relations, they do not have to pay taxes, which they consider these fees to be.
A Foreign Office spokesman said they did not believe there were any legal grounds to exempt diplomats from paying the congestion charge, adding: "The charge is comparable to a parking fee or a toll charge, which diplomatic missions and international organisations are required to pay."
And when it came to parking fines, he added: "Under the Vienna Convention on Diplomatic Relations, those entitled to immunity are expected to obey the law and we therefore expect all foreign diplomats to pay their parking fines.
"As the [foreign secretary's statement] points out, we have made a concerted effort to urge missions to pay their fines."
A US Embassy spokesman said staff "conscientiously pay fines for all traffic violations, such as parking and speeding violations".
"Our position on the [congestion charge] tax... is based on the 1961 Vienna Convention on Diplomatic Relations, which expressly prohibits the taxation of diplomatic missions in this manner," the spokesman said.
"This is a position shared by many other diplomatic missions in London. Our position is wholly in accordance with the convention, to which both the United States and the United Kingdom are parties."
The BBC has also contacted the Japanese and Nigerian embassies for a response.