The European Commission, which opened the investigation on Tuesday, said it had doubts about the overhaul. EU rules say a restructuring should ensure a company's long-term viability, that the firm shares some of the cost and that the state aid does not distort competition.

Romania sought EU approval for the restructuring in June 2017, which includes grants, subsidies, a debt write-off and a debt-to-equity conversion. These come on top of a 13.3 million euro rescue loan in 2016 which was cleared by the Commission.

Romania can be ordered to claw back the aid if it is found guilty of breaching EU rules.

(Reporting by Foo Yun Chee; editing by Robert-Jan Bartunek)