LONDON (AP) -- European Union diplomats were meeting Friday to finalize the draft divorce agreement between Britain and the bloc, amid a warning from Spain that it will oppose the deal if it isn't guaranteed a say over the future of Gibraltar.
Leaders of EU nations are due to meet Sunday to sign off on the deal, which lays out the terms of Britain's departure in March and sets up a framework for future relations. But Spain remains unsatisfied.
Spanish Prime Minister Pedro Sanchez tweeted that Britain and Spain "remain far away" on the issue and "if there are no changes, we will veto Brexit."
Spain wants the future of the tiny territory at the tip of the Iberian Peninsula — ceded to Britain in 1713 but still claimed by Spain — to be a bilateral issue between Madrid and London. Spanish officials are concerned that a key clause in the agreement referring to U.K.-EU negotiations on their future relationship makes no mention of Gibraltar.
Spain doesn't have a veto on the withdrawal agreement, which does not have to be approved unanimously. But it could hold up a future free-trade deal between Britain and the EU, which would require approval of all 27 EU nations.
Chief Minister of Gibraltar Fabian Picardo criticized Spain's insistence on a written guarantee, saying "Gibraltar has demonstrated that we actually want a direct engagement with Spain on issues."
"Spain is the physical and geographical gateway to Europe for Gibraltar," Picardo told the BBC. "We recognize that and there is absolutely no need for us to be vetoed into being brought to the table."
If EU leaders rubber-stamp the deal, it needs to be approved by the European and British Parliaments — a tough task for British Prime Minister Theresa May, whose Conservatives lack a majority in the House of Commons.
May was answering calls on a radio phone-in Friday in a bid to win public support for the divorce deal, which has been slammed by pro-Brexit and pro-EU politicians alike.
Brexiteers think the agreement will leave the U.K. tied too closely to EU rules, while pro-Europeans say it will erect new barriers between Britain and the bloc — its neighbor and biggest trading partner.