Spain would reject any attempt by Nicola Sturgeon for Scotland to stay in the EU single market if the rest of the UK comes out, one of the country’s most powerful MEPs warned last night.

Esteban Gonzalez Pons, who leads the Spanish delegation of MEPs in the European Parliament’s largest political grouping, told the Telegraph that Ms Sturgeon’s proposals for a special Scottish deal are “impossible.”

He said the Spanish government would oppose any plan by SNP ministers to stay in the EU single market if the rest of the UK leaves for fear of encouraging its own separatist movements in areas like Catalonia and the Basque Country.

In a major blow to the First Minister, he said the Spanish government is planning to be the United Kingdom’s “best friend” during the Brexit negotiations and they share “the same point of view about the Scottish question.”

The MEP, who sits on the parliament’s constitutional affairs committee, also echoed academic warnings that Ms Sturgeon’s plan would create a hard border between Scotland and England.

His intervention is significant as any special deal for Scotland, including membership of the European Free Trade Association (EFTA) and the European Economic Area (EEA), would require the consent of all EU member states.