British motorists planning to drive abroad in EU countries must remove any GB stickers from their vehicle, as new laws come into effect.
The old sticker used on the back of vehicles is no longer valid and drivers must replace it with a new "UK" one to drive on foreign roads.
The government informed the UN in July that the move would come into effect from September 28, this year.
RAC spokesperson Rod Dennis said: "It might only be a matter of replacing two letters, but this is a significant change for drivers who in normal times take their cars outside the UK.
"Any driver with a GB sticker on their car now needs to replace it with a new UK one if they are taking their vehicle abroad. Drivers also need to remember that number plates featuring the blue band and letters 'GB' next to the European golden stars are also no longer valid."
What do I need to do if I take my car abroad?
a GB identifier with the Union flag
a Euro symbol
a national flag of England, Scotland or Wales
numbers and letters only - no flag or identifier
However, if your number plate already includes a UK identifier with the Union flag - also known as the Union Jack - you do not need to add a sticker when travelling in most EU countries.
"If you’re in Spain, Cyprus or Malta, you must display a UK sticker no matter what is on your number plate," the government guidance adds.
"If you have a GB sticker, cover or remove it before driving outside the UK."
Why has the government changed the rules?
A DfT spokesperson said: “Changing the national identifier from GB to UK symbolises our unity as a nation and is part of a wider move towards using the UK signifier across government.
“We notified the UK of our intention to make these changes in July, and have been working with the sector to implement the change.”
The move comes after the government announced in January the EU flag would be removed from UK car number plates and driving licences to mark the first anniversary of Brexit.
UK drivers had been told that they wouldn’t need to display a GB sticker when driving in most EU countries if their number plate displays GB, or GB along with a Union Flag.
British motorists with photocard licences were also informed they do not need an international driving permit to drive in any of the 27 EU member states, along with Iceland, Norway, Switzerland and Liechtenstein.The Department for Transport said the changes were made to "signify the beginning of a new chapter for the UK" and was a "reassertion of our independence from the EU".Transport Secretary Grant Shapps added: "Looking to the future, whether it’s for work or for holidays abroad, these changes mean that those who want to drive in the EU can continue to do so with ease."