CLARA Ponsati, the former Catalan government minister facing extradition to Spain, has told SNP members a referendum can never be illegal in a democracy.

Ponsati is being sought by the Spanish authorities on charges of violent rebellion and misappropriation of public funds over her role in Catalonia's independence ballot last year.

Appearing at a packed-out fringe event at the SNP's conference in Aberdeen, she defended the decision of pro-independence leaders to pursue the unofficial referendum in October last year.

"A referendum is never illegal in a democracy and it's not illegal in Spain," she said.

"It was not an agreed referendum, that's true. We could not manage an agreement with the Spanish authorities to organise an agreed referendum like the one you had about your own independence."

Ponsati, an academic at St Andrews University, said the Spanish authorities had ignored demands for a vote despite the electorate giving the Catalan parliament a mandate.

"The voters have given us a mandate, we were obliged to do it," she said.

She accused the Spanish authorities of "manipulating" the reading of the law in bringing charges against those involved in the vote.

"What is illegal is what the judiciary are doing in Spain right now," she said.

"At the end of the day, yes, there is an article in the Spanish constitution that was approved many, many years ago and has not been revisited, that says that Spain is a united indivisible kingdom.

"But human rights and self-determination as a human right are founding elements of the Spanish democracy.

"Spanish nationalism, in their desperate defence of this sacred unity, are ready to sacrifice democracy."

Ponsati, who received a standing ovation from members, could face a total sentence of up to 33 years if she is sent to Spain and convicted of the charges, sparking fears the 61-year-old could spend the rest of her life in jail.

A full hearing of her extradition case is due to begin on July 30 at Edinburgh Sheriff Court.

Her lawyer, Aamer Anwar, who appeared at the fringe event alongside her, said the pressure was on to raise a further £230,000 for her defence, with crowd-funding already bringing in £270,000.

Ponsati was also cheered as she appeared on stage at the SNP conference soon after the fringe event.