European regulators announced an “in-depth investigation” into tens of millions of euros of potentially illegal Hungarian state aid for national airline Malev.

The formal probe will examine a string of support measures granted by Budapest to the troubled carrier, summed up as “several capital injections and shareholder loans” throughout privatisation and subsequent re-nationalisation.

“In particular, the commission has doubts that Malev would have been able to obtain financing from the market on the terms conceded by the Hungarian authorities,” competition officials said in a statement.

The Hungarian State Holding Company said in September that the Hungarian government had already injected a total of €52.5 million into the ailing company.

Privatised in 2007, Malev was effectively re-nationalised in February when the Hungarian state bought a 95 per cent stake in the debt-ridden airline from its Russian-backed owner, the AirBridge consortium.

After a “preliminary investigation,” the commission said it “also has doubts as to whether these measures meet the criteria of the commission’s guidelines for the rescue and restructuring of firms in difficulty”.

In 1997, the Hungarian state had already come to its rescue when it had bought the national carrier back from Italy’s Alitalia, which had acquired it in 1993.