TENSIONS are rising over the Catalan crisis as allies sprung to the defence of Spanish prime minister Pedro Sanchez for sanctioning a mediator to facilitate dialogue between the Madrid and Barcelona governments.

His Socialist party (PSOE) struck a deal with Catalan president Quim Torra’s administration to smooth the way for budget talks that need the backing of pro-independence MPs from the Republican Left of Catalonia (ERC) and the Democrats PDeCAT.

Sharp rebukes and outrage came from the centre-right opposition and his own party, but deputy PM Carmen Calvo tried to play it down.

She told SER Radio: “It’s not a mediator; this is not an international conflict. There’s a table where the Catalan parties will sit at that will use a person to help organise and negotiate. Nothing more.”

She later told a press conference: “There was an overwhelming clamour in our society from those who considered that the situation in Catalonia had reached an unacceptable extreme due to the vacuum of politics and dialogue.

“To continue building Spain with Catalonia as a part of it means to recognise reality, to work and use politics as a means so that all Catalans can feel that their day-to-day problems have an answer.”

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Leader of the right-wing Popular Party (PP), Pablo Casado, was among the most vocal critics of Sanchez. He told the EFE news agency that appointing a mediator was the “gravest event” since the failed coup attempt of February 23, 1981, when more than 200 Civil Guards armed with submachine guns and pistols burst into the lower house of parliament and held the cabinet and MPs hostage for 18 hours.

Casado described Sanchez as “the greatest traitor to the historical continuity of Spanish democracy” and a “felon” while describing his government as illegitimate.

The National: Spanish premier Pedro SanchezSpanish premier Pedro Sanchez

He urged the PM to call a general election or his party would break off all talks with the Socialists.

Asked if the PP would push for a vote of no-confidence against Sanchez’s cabinet, Casado said: “We aren’t ruling out anything.”

However, Josep Borrell, the unionist Catalan who is Spain’s foreign minister, defended his boss on Twitter: “Neither the Spanish Constitution, nor the Treaties of the #UniónEuropea, nor the international law, protect the secession of #Cataluña. To seek to negotiate a supposed right to self-determination as a counterpart to the approval of budgets is a categorical absurdity.

“The accusations [against Sanchez] of high treason and felony … are absolutely unjustified and unacceptable. Not only do they show a total lack of sense of state but also a sense of reality and sanity.

“This space of dialogue between representatives of the Catalan political parties does not affect at all the institutions of the State or the relations between the government and the Generalitat [Catalan Government], which continue to be developed in the current legal framework.”

Meanwhile, judges in Spain’s Supreme Court, where the Catalan political prisoners’ trial will begin next week, have refused to accept more than 50 witnesses for the defence, including Nobel Prize winners and senior figures from the United Nations.

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The seven judges, presided over by Manuel Marchena, have accepted most of the evidence proposed by state prosecutors and the far-right Vox party.

Former Spanish PM Mariano Rajoy, will be a witness, along with his former deputy Maria Sáenz de Santamaría, but Carles Puigdemont, the former Catalan president, will not be able to leave his exile in Brussels.

Catalan ombudsman, Rafael Ribó, who has been vocal in his criticism of rights violations during the Catalan independence referendum, will not be allowed to take to the witness stand.

The court said his reports can be found online and they did not need “complementary explanations” from him.

Three UN special rapporteurs have been excluded, along with Nobel Prize winners Jody Williams and Ahmed Galai.

Linguist Noam Chomsky, sociologist Richard Sennett and historian Paul Preston have also been told they cannot give evidence at the trial.