Police officers entered the Madrid headquarters of Spain's ruling Socialist Party (PSOE) on Wednesday to search for information about a potential illegal payments scheme, the Civil Guard said.

This comes as Prime Minsiter Pedro Sanchez's party is being buffeted by a series of graft allegations, includingallegations of impropriety by former Spanish Prime Minister Jose Luis Rodriguez Zapatero.

The news has put pressure on Sanchez's government and prompted protests in Madrid over the weekend. The allegations impact several members of the PM's inner circle, including his wife and brother.

Civil Guard officers searched the PSOE party headquarters on the upscale Calle de Ferraz street in Madrid on Wedneday Image: Diego Radamés/Europa Press/IMAGO

What did police say about the operation?