EUROPEAN Union leaders have been attacked by MPs for their “shameful” behaviour as they were accused of trying to give Spain a veto on the future of Gibraltar as part of the Brexit talks.

One Conservative backbencher insisted there would be “no sell-out” while another made clear there would be “no negotiation” over the status of the overseas territory.

Labour’s Mary Creagh, a leading supporter of Open Britain, which campaigns for maintaining close links with the EU, insisted Gibraltar “must not become a victim of Brexit”.

While Tom Brake for the Liberal Democrats said the apparent veto showed “just how damaging the Government's hard Brexit will be on this strategically-important British territory”.

He added: "Theresa May must urgently produce a plan that protects the citizens of Gibraltar, including their businesses and communities.”

The Brexit Department responded by simply pointing to the remarks the Prime Minister made on Wednesday when she said the UK would be "absolutely steadfast" in its support of Gibraltar, its people and its economy. Mrs May also said: "We have been firm in our commitment never to enter arrangements under which the people of Gibraltar would pass under the sovereignty of another state against their wishes, nor to enter into a process of sovereignty negotiations with which Gibraltar is not content.”

The row was sparked after Donald Tusk, the President of the European Council of leaders, in the guidelines published by Brussels ahead of the Brexit talks, stated that no agreement between the EU and the UK will apply to Gibraltar unless agreed by Madrid.

The status of the Rock is addressed in a single paragraph of Mr Tusk's nine-page document, which says: "After the United Kingdom leaves the Union, no agreement between the EU and the United Kingdom may apply to the territory of Gibraltar without the agreement between the Kingdom of Spain and the United Kingdom."

Spain has a long-standing territorial claim on Gibraltar, which has been held by the UK since 1713 and currently has the status of British Overseas Territory.

Any suggestion Madrid might have a say over the status of the self-governing territory, which is home to important UK military bases, is likely to raise concerns among its 30,000 inhabitants.

Gloucestershire Tory MP Jack Lopresti, who chairs the all-party parliamentary group on Gibraltar, said: “It’s predictable that given Spain’s previous behaviour, they would try and use Brexit as a fig leaf for trouble-making over the status of Gibraltar.

“It is shameful that the EU have attempted to allow Spain an effective veto over the future of British sovereign territory, flying in the face of the will of the people of Gibraltar. The UK Government’s position is clear and will stand. There will be no negotiation over the status of Gibraltar.”

Fellow Conservative Bob Neill, a London MP, added: "Gibraltar's friends in the UK will be watching this very carefully. There will be no sell-out."

Ms Creagh said “Brextremists” should be ashamed of their actions, which had destabilised the situation in Gibraltar whose future was now up into the air.

“The Rock depends on free movement of labour from Spain and on its place in the single market to support its vital services industries.”

The Wakefield MP added: “Ministers should listen to the First Minister of Gibraltar, who this week said that Gibraltar should be no bargaining chip in, pawn in or victim of Brexit. At the moment, the Rock risks being treated as all three.”