Pujol pushed for — and won — greater powers for Catalonia when he served as president of the government of the wealthy northeastern region of Spain between 1981 and 2003, winning him the nickname of "Spain's viceroy".

He spent two years in jail for having helped to organize the singing of a banned Catalan anthem at Barcelona's Palau de la Musica concert hall in front of Franco, cementing his image as one of the leading opponents to the dictatorship which suppressed Catalan autonomy, culture and language.

But 10 years after he left office, his image as the patriarch of Catalan identity is overshadowed by allegations of wrongdoing involving his sons at a time when Catalonia is experiencing a resurgence in its independence movement.

Oriol Pujol, the fifth of his seven sons, appeared before a judge in Barcelona on Tuesday after he was charged last month with influence peddling.

Spanish authorities suspect the 46-year-old of using political prominence over the assignment of vehicle inspection centre contracts for personal gain.

Oriol, the only one of Jordi's sons to enter politics, says the charges are politically motivated to discredit the independence movement.

"I have always acted strictly within the law. I have never cooperated with any corruption network," he said when he was charged.

Oriol is seen as a likely successor to Catalan President Artur Mas, who has broken with his ruling Convergence and Union (CiU) party's long tradition of moderation and is now pushing for a referendum on independence from Spain.

He has a seat in the Catalan regional parliament in representation of the party, which his father helped to found in 1974, a year before Franco's death paved the way for the restoration of democracy in Spain.

Oriol's older brother Jordi, a 54-year-old fan of luxury cars, is under investigation after it was revealed that he moved €32.4 million to bank accounts in 13 nations, including tax havens such as Andorra, Luxembourg and Liechtenstein. He has not been charged with any crime.

In January his former girlfriend Victoria Alvarez told an investigating judge that she transported €400,000 in €200 and €500 notes in a bag from Andorra, according to Spanish media reports.

"He usually carries a lot of cash. He normally has between €6,000 and 10,000 in his pockets," she said during questioning by the judge, according to daily newspaper El País.

The affair came to light after a detective agency used an electronic device hidden inside a bouquet of flowers to record a conversation between Alvarez and Alicia Sanchez-Camacho, the head of the Catalan branch of the conservative Popular Party, at a Barcelona restaurant.

During their conversation, Alvarez discussed the details of her former boyfriend's bank accounts outside of Spain and their conversation was leaked to the press.

Jordi Pujol said Friday he was "worried" because of the scandal affecting his sons.

"But I am confident in the outcome," the 82-year-old added.

Before the last regional elections held in Catalonia in November 2012, an alleged police report whose origins were unknown was published in daily newspaper El Mundo which claimed that Mas and Pujol had bank accounts in Switzerland. The banks cited by the newspaper denied the report.

Suspicions of corruption affecting the Pujol clan are not new.

"About one-fifth of the 58 members of Pujol's governments during the 23 years in which he was president were investigated for corruption. Its shocking," said University of Carcelona political scientist Jordi Matas.

"If the region wants to advance on its path to self-determination, these types of practices, if they exist, must be eliminated," he added.