Luis Barcenas, former treasurer of Spain's acting governing People's Party (PP), arrives to testify in the Gurtel corruption case at High Court in San Fernando de Henares, outside Madrid, Spain, October 4, 2016. REUTERS/Susana Vera

MADRID (Reuters) - The former treasurer of Spain’s ruling People’s Party, Luis Barcenas, was given a 33-year prison sentence and fined 44 million euros on Thursday for his part in a corruption case in which dozens of high-ranking party members were jailed on Thursday.

The case, which relates to the use of a slush fund by the Conservatives in the 1990s and early 2000s to illegally finance campaigns, has plagued Prime Minister Mariano Rajoy, who has denied any wrongdoing ever since he came to power in 2011.

Rajoy became the first sitting prime minister in Spain to give evidence in a trial when he was called as a witness in the case in July last year, prompting calls for his resignation.

Twenty-nine of the 37 accused were convicted of offences including falsifying accounts, influence-peddling and tax crimes, and they were sentenced to a combined 351 years behind bars, according to a court ruling.

Former PP treasurer Barcenas was convicted of money laundering, personal enrichment and a number of tax crimes. His wife Rosalia Iglesias faces 15 years in prison.

The case originally centered on illegal dealings between small city councils and a network of businesses, and later became known as the “Gurtel case” after the nickname of Francisco Correa, a businessman seen as the head of the kickback scheme. Correa was handed a 51-year sentence.