Gibraltar warns of hard Brexit 'existential threat' to its economy

"A hard Brexit would be really an existential threat to the Gibraltar economic model," Mr Picardo told the BBC Radio 4 Today programme.

"What might be a disastrous exit for the United Kingdom would be an existential threat to Gibraltar's current economic model."

Gibraltar, which relies upon thousands of Spanish workers crossing into the territory every day, voted overwhelmingly to remain in the EU in the June 23 referendum.

The Gibraltar government is already in discussions with Scotland - which also voted strongly for Remain - about what kind of arrangements they could have with the EU once the UK finally leaves.

Mr Picardo said one possibility could be to do a "reverse Greenland" - a self-governing territory which is part of Denmark but which left the EU in 1985 following a referendum vote.

"We have been talking about this possibility of what has been described as a 'reverse Greenland' which envisages one part of a member state leaving the European Union because it chooses to do so and other parts of the member state remaining, with access to the single market and freedom of movement being the things that matter most to us," he said.

"What Gibraltar is looking at is what type of participation we can have in the European Union or with the European Union, once the United Kingdom has decided what its Brexit looks like."

Mr Picardo strongly rejected suggestions that it would have to concede some form of joint sovereignty to Spain - something it has long opposed - if it was to continue to enjoy unfettered access to EU markets and labour.

"We are not worried because we have seen this sort of bloody-minded attitude before," he said.