The brother of Spain’s prime minister has been banned from holding public office for nine years after being found guilty of administrative misconduct relating to his hiring by a socialist-led council in the south-western region of Extremadura nine years ago.

Corruption allegations involving Pedro Sánchez’s family, his government and his Spanish Socialist Workers’ party (PSOE) have triggered repeated opposition calls for a snap general election. All the accused have denied wrongdoing.

David Sánchez, a composer and orchestra conductor, was one of 11 people who went on trial in May accused of influence peddling and misuse of office. The case originated with a complaint brought by Manos Limpias (Clean Hands), a self-styled trade union with far-right links that has a long history of using the courts to pursue those it deems to pose a threat to Spain’s democratic interests.

According to the complaint, David Sánchez was handed a bespoke job as coordinator of public music schools by the socialist-led council of the south-western province of Badajoz in July 2017, when his brother was the national leader of the PSOE but not yet prime minister.

Sánchez, who had denied the charges, was found guilty of administrative misconduct but cleared of influence peddling by a court in Badajoz on Tuesday.

In its ruling, the court said the creation of the job to which he had been appointed had not been “necessary or urgent”, adding that it had been developed “in the particular interest of its assignee and not in the general interest”.

But it also ruled that it had not been proved that “anyone had exerted pressure or influence … [nor that] anyone had taken advantage of the exercise of the powers of a position or any other situation derived from a personal or hierarchical relationship”.

Had Sánchez been found guilty of influence peddling, he could have faced a three-year prison sentence. Nine of his co-defendants were also found guilty of administrative misconduct and handed nine-year bans from public office, while Miguel Ángel Gallardo, the PSOE’s former leader in Extremadura, was banned from holding public office for 18 years after being found guilty of two counts of misconduct. The verdicts can be appealed.

Pedro Sánchez has previously accused his political and media enemies of launching a “harassment and bullying operation” against his family.

His wife, Begoña Gómez, has been accused of using her influence as the wife of the prime minister to secure and manage a post at Madrid’s Complutense University, and of using public resources and personal connections to further her private interests. She faces trial after a judge charged her with embezzlement, influence peddling, corruption in business dealings and misappropriation of funds at the end of a two-year investigation.

The prime minister has maintained that his wife and brother are the victims of politically motivated smear campaigns, and has said: “The truth will come out in the end. My brother and my wife are innocent.”

He has also openly questioned the independence of some members of Spain’s judiciary. “There’s no doubt that there are judges doing politics and there are politicians trying to do justice,” he said in a TV interview last September.

Alberto Núñez Feijóo, the leader of Spain’s conservative People’s party (PP), said this was the third case in which a member of the prime minister’s circle had been convicted.

In November last year, Spain’s attorney general, Álvaro García Ortiz, was banned from his post for two years after being found guilty of leaking confidential information about a tax case involving a businessman who is the boyfriend of a prominent rightwing politician. At the end of June, the former PSOE transport minister José Luis Ábalos was jailed for 24 years for taking bribes on public contracts for sanitary equipment such as ‌face masks during the Covid pandemic.

“It speaks well of our rule of law that no one is above the law, no matter which family they belong to,” said Feijóo. “That should comfort Spaniards.”

Santiago Abascal, the leader of the far-right Vox party, greeted news of David Sánchez’s conviction by once again labelling the PSOE a “mafia”.

The government’s outspoken transport minister, Óscar Puente, hit back, suggesting the socialists’ opponents were using the courts to achieve what they could not manage in polling stations.

“The period will be studied in history books as a time when the seams of our most important institutions were strained with the sole purpose of bringing down a government because some people couldn’t do it at the ballot box,” he said.