Divisions among EU member states over the Brexit deal have been exposed after Spain threatened to veto the agreement over its provisions on Gibraltar.
EU chief negotiator Michel Barnier has so far been able to maintain a united front in negotiators despite the disparate interests of the 27-member states.
But he faced a public rebellion on Monday as Spain demanded Barnier make changes to the draft withdrawal agreement in relation to Gibraltar.
The EU’s negotiating guidelines published last year stated that any deal on the future relationship between the UK and EU would not apply to Gibraltar without the consent of Spain.
Spain is unhappy that the draft withdrawal agreement published last week is not consistent with that position and has warned it won’t back the deal at Sunday’s summit without changes.
“The negotiations between Britain and the EU have a territorial scope that does not include Gibraltar, the negotiations on the future of Gibraltar are separate discussions,” said Spain’s foreign minister Josep Borrell.
“This is what needs to be made clear, and until it is clarified in the withdrawal agreement and in the political declaration on the future relationship, we cannot give our backing.”
The issue risks causing a row at Sunday’s summit which is meant to simply rubber stamp the agreement, one EU diplomat warned.
If Barnier is forced to back down, it could encourage other member states to push for their own last-minute amendments.
Ministers from the EU27 formally approved the draft deal during a meeting with Barnier in Brussels on Monday.
But France is leading a group of states which wants guarantees on continued access to UK waters for their fishing industry after Brexit as part of the agreement.
Barnier has been able to convince EU ministers that these issues should be resolved in the negotiations on the future relationship that will begin after Brexit.
So far, they have agreed to put their concerns on ice so as not to increase the chances of the Brexit deal hitting the rocks but might now reopen the issue.
Czech Europe minister Ales Chmelar said some states “have some individual proposals on sensitive issue” but said: “We hope that the text will not be reopened excessively.”