First Minister Nicola Sturgeon has told MSPs she is "concerned" about the banning of a referendum on Catalonian independence and the subsequent arrests of several of the state's ministers.

The region's pro-independence government has organised a vote on independence to be held on October 1, but the poll has been found to be illegal by the Spanish Constitutional Court.

The nation's constitution states the country is bound in "indissoluble unity" and therefore regions cannot unilaterally declare independence.

In recent days Spanish police have arrested those ministers organising the vote, raided properties to confiscate ballot papers, posters and other materials relating to the vote.

Around 7.5 million people live in the state which is one of Spain's most prosperous regions.

Speaking at First Minister's Questions on Thursday, Sturgeon said: "I think most people would agree that the situation in Catalonia is of concern.

"I hope that there will be dialogue between the Catalan and the Spanish governments to try to resolve the situation. That has got to be preferable to the sight of police officers seizing ballot papers and entering newspaper offices.

"It is of course entirely legitimate for Spain to oppose independence for Catalonia but what I think is of concern anywhere is for a state to seek to deny the right of a people to democratically express their will.

"The right of self determination is an important international principle and I hope very much that it will be respected in Catalonia and everywhere else.

"The Edinburgh Agreement is a shining example of two governments with diametrically opposed views on independence nevertheless coming together to agree a process that allowed the people to decide and I think that offers a template that can be used by others elsewhere in the world."

A pro-Catalan protest took place in Glasgow on the Buchanan Street steps later on Thursday.