Catalonia’s pro-independence government has accused Spain of spying on its internal communications with its UK diplomatic mission, after foreign ministry documents revealed Catalan plans to "get closer to Nicola Sturgeon".

Alfred Bosch, the foreign affairs chief for the Catalan government, said documents filed by Madrid in a court bid included summaries of confidential exchanges between Catalan leaders and diplomats.

He challenged Spanish Foreign Minister Josep Borrell to state publicly what state resources were being used to spy on Catalan politicians “here and in Europe”. As well as the British mission, those in Germany and Switzerland had also been subject to surveillance, Mr Bosch claimed.

“Borrell must show his face and take responsibility for what we know. And if necessary, he must resign,” Mr Bosch said in Catalonia’s parliament on Wednesday.

Mr Borrell, who has been nominated by the Council of the European Union to become the EU’s next foreign policy chief, is a stern opponent of independence for Catalonia.

Mr Bosch’s department points to Spanish Foreign Ministry documents submitted by the Spanish Solicitor General’s Office in its legal bid to have Catalonia’s missions in London, Berlin and Geneva closed down.

In one document published by the online newspaper eldiario.es, Sergi Marcén, the Catalan delegate in the UK, is told by Mr Bosch’s department to “get closer to Nicola Sturgeon” to promote the idea of a “memorandum of understanding between Catalan and Scottish governments”, as well as contacting the leaders of Amnesty International in Britain and the PEN International human rights organisation.