A probe has found "serious irregularities" around infrastructure projects linked to the son-in-law of Hungarian Prime Minister Viktor Orban.

OLAF, the EU’s anti-fraud agency, carried out a two-year investigation into 35 schemes aimed at improving public lighting in Hungary.

The projects were awarded to Elios Innovative Zrt, a company co-owned by Istvan Tiborcz, who married Orban’s eldest daughter, report Hungarian media.

They were part-financed by the European Union and OLAF’s claims could prompt Brussels to try and claw back payments on the projects of more than €40 million.

A spokeswoman for OLAF told Euronews: “OLAF has finalised its investigation into possible irregularities related to 35 lighting projects implemented under the Hungarian Environment and Energy Operational Program, and co-financed by the European Cohesion Funds.

“The scope of the projects was to renovate the public lighting infrastructure in various Hungarian Municipalities using environmentally friendly and power-saving LED technology products.

“OLAF's investigation revealed not only serious irregularities in most of the projects, but also conflict of interest.

“OLAF sent its final report containing financial recommendations to the European Commission Directorate-General for Regional and Urban Policy, and judicial recommendations to the General Prosecutor of Hungary.”

It comes as EU countries consider how they are going to fill a hole in the bloc’s budget, created by the UK’s planned exit next year.

Late last year a quartet of EU heavyweights called on Brussels to cut funding to Hungary until the country until “basic democratic freedoms are reinstated”.

'In compliance with legal requirements'

Elios issued a statement on the allegations on February 7, saying: "Elios Innovative Zrt performed every mandate in compliance with legal requirements and at a high level of professionalism."

It added that the company is working together with authorities in the investigation — but said it doesn't comment on "politically-driven questions from the press".

After meeting Austrian Chancellor Sebastian Kurz in Vienna on January 30, Orban was asked to clarify the government's stance on the investigation. When asked by a Hungarian newspaper to comment on the "serious irregularities" found by OLAF involving his son-in-law, Orban said, "Hungary's stance, as in every such case, is clear: the necessary investigations must be carried out."