Spain’s Foreign Minister Alfonso Dastis has said it wants a bilateral deal with the UK to jointly manage Gibraltar’s airport after Britain leaves the European Union.

“Sovereignty is something we aspire to, that we are not renouncing, but in these negotiations it is not the issue,” the Spanish minister was quoted as saying by the Financial Times.

It was also reported that the Spanish proposal is likely to be highly contentious for London, which has long maintained that the airport is a British asset on British land. Previous talks about enlarging the airport so it is also on Spanish land have fallen through.

The Brexit talks between the UK and the EU have given new urgency to the dispute over Gibraltar, ceded to Britain under the 1713 Treaty of Utrecht.

The issue of the airport is even more fraught, since it is located on the isthmus that connects the rock of Gibraltar with the Spanish mainland — land that Madrid considers illegally occupied by the UK. Dastis said that Spain “has a claim” to the land.

He also said a deal on Gibraltar would not have to be completely resolved by crucial summit next month, in which Britain hopes to agree the broad terms of a transition period, but would have to be struck before the final withdrawal agreement is closed later in the year.

According to the Financial Times, the two governments have repeatedly failed over the past 40 years to reach a lasting deal on the airport.