Spain is to be given an effective veto over the future of Gibraltar as part of the Brexit plans.
The idea has prompted anger among some British critics.
Under draft guidelines drawn up by EU leaders, it states that the Brexit deal will not apply to Gibraltar, without an “agreement between the Kingdom of Spain and the UK”, reports the Telegraph.
British officials argue that it should not be included in any joint agreement between the UK and the 27 other EU nations, as it is a bilateral issue between Madrid and London.
The vice-chair of the All-Party Parliamentary Group for Gibraltar, Andrew Rosindell, said the joint agreement was an attempt to bully Britain.
“British people must and will stand together, we cannot be bullied by Spain, any agreement must apply equally to the whole British family and that includes Gibraltar,” he said.
“There can be no compromise on this.”
Draft draft negotiating guidelines for withdrawal talks state that “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.”
The issue taps into a long-held fear in the British territory, which has warned it will not be used as a bargaining chip in any Brexit deal.
Last year, Spain’s acting foreign minister Jose Manuel Garcia-Margallo said he hoped “the Spanish flag on the Rock” was closer to reality following the vote to leave the EU.
Although staunchly British, Gibraltar, which has been a British territory since 1713, voted overwhelmingly to stay with Brussels last year.
Of its 30,000 residents , 97% voted to remain in the EU.