Businessman Víctor de Aldama has submitted a 37-page document to Spain's Supreme Court, alleging the involvement of former Transport Minister José Luis Ábalos in a corruption network.

The document claims Ábalos pre-awarded public contracts to certain companies in exchange for illegal commissions.

It also details a supposed agreement to gift Ábalos a luxury apartment valued at 1.9 million euros.

Aldama, previously released after a court appearance, accuses other high-ranking PSOE officials of benefiting from the scheme.

The Supreme Court has summoned Ábalos to testify on December 12, as investigations intensify.