The figures show several embassies owe money for the charge
US diplomatic staff in London have run up unpaid congestion charge fees of £271,000 in the past six months, new figures have revealed.
Transport for London (TfL) said embassy staff, the subject of a bitter tirade from London mayor Ken Livingstone, have jumped high up the debt table.
The US embassy has said it does not intend to pay the fees, instead claiming diplomatic privilege.
The figures were released under the Freedom of Information Act.
The mayor said US staff should pay the congestion charge as UK staff pay road tolls in the US.
UNPAID CHARGES OCT '05 - APRIL '06
1. US £271,000
2. Nigeria £202,150
3. Angola £127,150
4. Sudan £94,250
5. Switzerland £52,300
The new figures show that many millions of pounds are owed in total by several of London's 160 embassies since the introduction.
The US embassy is number one on the list for fees not paid in the past six months.
And the figures show that the Angolan embassy owes more than half a million pounds in unpaid congestion charge fees since the scheme was introduced in February 2003.
'This is not a tax'
A spokesman for TfL said: "We are continuing to seek payment for any outstanding debts from embassies refusing to pay.
"Last month the United Arab Emirates embassy accepted the principle and have joined the many other embassies who have agreed this is a legitimate charge.
"This is not a tax, it's a charge for a service and gives no privileges to any VIPs, so we do not see why diplomats should be exempt.
He said embassies were immune from clamping and bailiff action under the Vienna Convention, but TfL would continue to press for payment for money owing.