Spain's Socialist opposition is challenging Mariano Rajoy's government by filing for a vote of no confidence after judges ruled that the governing Popular Party profited from a large kickbacks-for-contracts scheme.

A party spokeswoman who wasn't authorized to be named in media reports confirmed the decision on Friday, one day after the National Court convicted 29 businesspeople and PP officials for fraud, tax evasion and money laundering, among other crimes.

The judges issued prison sentences totaling 351 years and fined the conservative PP 245,000 euros (US$ 287,000).

The Socialists' challenge will push the pro-business Ciudadanos (Citizens) party, which has until now supported the prime minister's minority government in parliament, to make a decision whether to back the vote. The anti-establishment Podemos party has already said it will vote to sack Rajoy.