A Madrid court on Tuesday issued a summons for the wife of Prime Minister Pedro Sanchez to appear on July 5 as part of a preliminary corruption probe into her business ties.

The move comes after the court last week rejected prosecutors' request to close the probe into Begona Gomez, indicating there was "sufficient" evidence to justify continuing the investigation.

The decision to open the probe was a setback for the premier but a boost for his right-wing opponents who see the move as vindication of their allegations that he and his left-wing government are corrupt.

"There is evidence that an alleged criminal offence was committed" which "goes beyond mere suspicion" and was "sufficient" to let the investigation continue, said court documents seen by AFP.

This contradicts a recent Guardia Civil police report which said it found no evidence of any criminal offence.

The court "has summoned Begona Gomez to appear as an investigated party on Friday 5 July at 10:00 am (0800 GMT) as part of a preliminary investigation into the alleged offences of corruption in the private sector and influence peddling," it said.

The court opened the probe into Gomez for suspected influence peddling and corruption on April 16 following a complaint filed by an anti-graft NGO linked to the far right.

The group, Manos Limpias (Clean Hands) says its complaint is based on media reports. It has previously filed a litany of unsuccessful lawsuits against politicians in the past.

The case centres on public contracts awarded to a businessman who had professional relations with Gomez.

Sanchez immediately denounced what he said was a political campaign seeking to "harass and discredit" him by "media heavily influenced by the right and far-right" and backed by the right-wing opposition.

When the court in April confirmed the probe, Sanchez said in a shock announcement that he would consider resigning. He took five days to reflect and in the end, decided to stay on.

The opposition denounced the move as pure political theatre, saying Sanchez had never had any intention of stepping down.

The leader of the main opposition conservative Popular Party (PP), Alberto Nunez Feijoo, said Monday he believes Sanchez should resign over the questions regarding his wife’s business dealings.

"Nobody believes he did not know her activities," he added during an interview with private television station Antena 3.

Shortly after the court said it has summoned Gomez, PP secretary-general Cuca Gamarra wrote on social media network X: "It is not mud, it is corruption".

"Spain deserves a worthy premier and Sanchez is not one," she added.