Britain could get visa-free access to the European Union for its citizens even after no-deal Brexit but objected on Friday to language used in the proposed EU regulation which described Gibraltar as a "colony".
The row highlighted strains over the territory on Spain's southern coast as Britain quits the Union and the remainder of the EU states swing the bloc's policies behind Spain, which is taking advantage of Brexit to ramp up its claim to "The Rock".
The new regulation would let British citizens can visit the EU without a visa for up to 90 days even if there is no special withdrawal deal.
It made a new distinction between those living in Britain and those who are citizens of Gibraltar, a British Overseas Territory which is now in the EU.
Diplomats said the British ambassador to the EU raised London's objections to this in a meeting of EU envoys. A British spokeswoman said: "Gibraltar is not a colony and it is completely inappropriate to describe in this way."
A spokesman for British Prime Minister Theresa May has said it is "unacceptable" to describe Gibraltar as a colony, adding; "it is part of the UK family".