A CROSS-party group of MSPs has condemned the Spanish Government's attempt to stop an independence referendum in Catalonia as a “violation" of democracy.

SNP, Labour, Green MSPs and Lib Dem politicians backed the region's right to hold the vote next Sunday, despite Spain's constitutional court saying it would be illegal.

In a letter to Spain's leader Mariano Rajoy Brey the 19 MSPs highlight concerns about the arrest of Catalan officials on suspicion of helping to prepare for the referendum.

They say the crackdown is an assault on democracy and "no way for a democratic European state to act against its own people".

The intervention by pro- and anti-independence MSPs represents one of the harshest condemnations yet from Scottish politicians of the crackdown.

Nicola Sturgeon backed the right of the Catalan government to hold the referendum and said the situation in Catalonia was "of concern" at Holyrood last week.

However, the letter from the MSPs explicitly criticises the Spanish government's action. It states: "As elected members of the Scottish Parliament, we are writing to express our grave concern at the escalating actions of the Spanish state in Catalonia.

"We come from a range of political traditions, with differing views on Scotland’s constitutional future and a collective neutrality on the question being posed to the Catalan people but we are united in our belief in democracy.

"The Spanish government claim to be acting in defence of democracy but threats of legal action against hundreds of democratically elected representatives and repressive acts against an elected Government, media organisations and citizens are in no way democratic acts.

"The recent arrest of a Catalan Government minister and a number of government staff was a particular violation of the norms of European democracy. Legal action against the Catalan government, several hundred local mayors and others perceived to be facilitating the referendum is no way for a democratic European state to act against its own people."

Green MSP Ross Greer, who organised the letter, warned the Spanish government that its crackdown was a "dark road to go down".

He said: “To see a state at the heart of Europe take such oppressive actions against its own people is simply unacceptable. The UK and Spain may be different places with different constitutional traditions but in Scotland we have proven that such significant questions can be answered through peaceful debate and dialogue."

Green MSPs Patrick Harvie, John Finnie and Alison Johnstone are signatories along with Greer.

The SNP MSPs are: Linda Fabiani, Kate Forbes, Mairi Gougeon, Clare Haughey, Ruth MaGuire, Gillian Martin, Christina McKelvie, Stuart McMillan, James Dornan and Sandra White.

Labour MSPs backing it are: Claudia Beamish; Neil Findlay and Pauline McNeill.

Scottish Lib Dem leader and Willie Rennie and another of the party's MSPs Alex Cole-Hamilton have also added their signatures.