SNP and Labour MEPs have joined forces to condemn Spain's prosecutions of pro-independence leaders in Catalan, including the arrest warrant issued for Scottish-based ex-minister Carla Ponsati.

The Scottish politicians set aside their differences on Scottish independence to warn EU authorities that they believed Spanish actions risked core EU values. 

Alyn Smith and Ian Hudgton of the SNP and Catherine Stihler and David Martin of Labour have signed a cross-party joint letter to EU Commission vice president Frans Timmermans, who is responsible for human rights, saying European arrest warrants issued for Ms Ponsati and other Catalan independentistes was "deeply concerning".

They wrote: "We wish to make clear to you that we believe that the measures being taken by the Spanish Government in regard to Catalonia put at risk the core values of the EU such as freedom of speech and assembly.

"Under different circumstances and within a very different context we in Scotland enjoyed a ‘gold standard’ referendum that was the product of genuine dialogue between Edinburgh and London. If our experience is of use, we are entirely at your disposal."

The Herald: Alyn Smith

Alyn Smith

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The letter was not signed by the two other MEPs representing Scotland, from the Conservatives and UKIP.

Some unionist politicians an activists have appeared to take Spain's side, especially on polarised social media. Former Labour spin doctor John McTernan was rebuked by Ms Ponsati's lawyer, Aamer Anwar, on Twitter for effectively declaring the St Andrews professor guilty of misusing public funds to hold the referendum.

However, both EU officials and British unionist politicians are understood to have misgivings about Spain's conduct, including its  violent disruption of an independence referendum it declared illegal last year. Previously former Conservative MEP Ian Duncan, now a Westminster minister, had urged compromise in Spain.

Tory minister Andrea Leadsom sent a coded message to Spain on Thursday when asked about the case in the House of Commons.

The government in Madrid has adopted a legalistic approach to its dispute with Catalonia's pro-indepndence leadership as a political solution, such as a Scottish-style approved referendum appears far away.

The four current MEPs in their letter added: "We must caution that the pursuit of democratically elected politicians across the EU using the European Arrest Warrant is deeply concerning and represents a disturbing continuation of the Spanish Government’s longstanding policies to prevent a referendum taking place in Catalonia.

"We would be grateful for your views on whether this is in fact an abuse of the European Arrest Warrant procedures.As MEPs we strongly oppose the Spanish Government’s decision to seek the arrest and imprisonment of political opponents.

"The Scottish Government external affairs secretary Fiona Hyslop has written to the Spanish Embassy in the UK expressing the Scottish Government's regret at the arrest warrants.

"We accept that there are legal processes that must be followed but these events reemphasise the real need for mediation between the two sides."

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Catherine Stihler

They told Mr Timmermans: "Events in Catalonia are of EU level significance. It will only be by dialogue and negotiation that a political solution can be found. The Commission is ideally placed to facilitate this and it is for that reason that we wish to repeat our request that you, a First Vice-President of the European Commission in charge of the Rule of Law and the Charter of Fundamental Rights, take the initiative and commence a dialogue that brings both sides to a political negotiation."

At Westminster, Commons Leader Andrea Leadsom urged the Spanish Government to “look carefully at the backdrop” to the cases of Carles Puigdemont and Clara Ponsati.

READ MORE: A Catalan view on how a St Andrews professor faces 30 years in a Spanish jail for 'sedition'

The issue was raised by Pete Wishart for the SNP who told MPs that in Scotland and across Europe people were being arrested “just for having a political idea and vision for their country”.

Referring to Ms Ponsatí, a professor at St Andrews University, who this week was arrested under a Spanish European Arrest Warrant, the Perth MP said: “Her crime was believing that her country would be a better place if it governed itself and, peacefully and democratically, making that her political aim.

“The UK is a country that hates state oppression, loves democracy and speaks out against injustice throughout the world, so can we have a statement on that, even if it is just to ask Spain to think about what it is doing and the reputational damage it is causing itself?” asked Mr Wishart.

Ms Leadsom replied that the Nationalist MP had raised a “really important point” about Catalan independence and the extradition warrant applied for against a Member of the Catalan Parliament.

“Spain is a key ally of the United Kingdom and, of course, we support its right to uphold its constitution. Nevertheless, I have some sympathy with him and we always urge every one of our allies to look carefully at the backdrop to these cases,” she added.