IMAGINE if the Westminster Government was to lock up First Minister Nicola Sturgeon or her predecessor Alex Salmond and other leading SNP figures.

That was the comparison used by a top lawyer yesterday when he declared that the imprisonment of leading figures in the Catalan independence movement was against international law.

Ben Emmerson QC said in London yesterday: “Imagine if the UK imprisoned the leaders of the SNP for advocating independence for Scotland.”

Referring to Franco’s dictatorship, he added: “These detentions are arbitrary and belong to a bygone era of Spanish history.”

Pressure is piling on the Spanish Government over their detention of leading figures in the independence movement in Catalonia after Emmerson revealed he was taking the case to the United Nations (UN).

Emmerson represents the former regional vice-president of Catalonia, Oriol Junqueras, and two prominent heads of pro-independence organisations, Jordi Cuixart and Jordi Sanchez. All three are in detention in Madrid facing charges of rebellion and sedition over their roles in last year’s referendum, which the Spanish Government banned and tried to brutally suppress.

Emmerson said: “Spain has brought unsustainable charges of sedition and rebellion against Catalonia’s leaders. Their detention is an affront to human rights, designed to prevent them from performing their role as political representatives of the Catalan people.

“This case does not ask the United Nations to adjudicate on the issue of Catalan independence, but seeks the UN’s reaffirmation that governments cannot repress political dissent through arbitrary detention.

“If you go around imprisoning those who advocate political change, then you are undermining the foundations of democracy.”

Emmerson has filed a 26-page complaint with the UN Working Group on Arbitrary Detention, emphasising that the trio’s actions were non-violent.

Meanwhile, the Catalan parliamentary speaker Roger Torrent said yesterday that “no court can decide who will be the president of Catalonia”.

The elected president of Catalonia, Carles Puigdemont, left Spain for Belgium before he could be detained but faces arrest on possible charges of sedition, rebellion and misuse of public funds should he return to Spain.

However, he remains the sole candidate for the Catalan presidency following December’s regional election, in which the three pro-independence parties retained their majority.

Also yesterday, Junqueras suggested that it might be possible for Puigdemont to serve as president in a symbolic capacity, even though the Spanish Government opposes his return to office.

Were Puigdemont to be sworn in again, Junqueras said in an interview with the online news outlet Diario16, it could result in “a legitimate, if symbolic, presidency” that worked in tandem with a day-to-day executive in Catalonia.

Spain fell sharply in a recent annual Democracy Index by the Economist Intelligence Unit, which cited Spain’s use of force in an attempt to stop the referendum going ahead and a repressive treatment of pro-indpendence politicians, but it was clear yesterday that the European Union still supports the Spanish Government.

Frans Timmermans, vice-president of the European Commission, insisted that Brussels would not be “used by people who have a domestic agenda which is directly a change to the constitutional order of a member state”.

Timmermans admitted, however, that it was clear that the violent conduct of Spanish police on the day of the referendum had “led to a lot of concerns in the EU”.

He insisted that the Commission had no criticisms about the rule of law in Spain, nor democracy and human rights, and that those who wanted change had to fight for it within the law.

Those words could come back to haunt him if, as many legal experts expect, Spain is found to be in breach of international laws.