The company has been going through Adria's books for almost two weeks and is expected to reach a decision by the end of the summer, 24ur.com reported late on Tuesday, quoting "unofficial but reliable sources".

"Due diligence and negotiations with a potential investor are being carried out. We are confident at Adria that a transaction will be successfully completed," 24ur.com quoted Adria as saying.

Mesa Airlines told the portal it could not comment on potential transactions given that they are a listed company.

Siol.net later reported that the US carrier had been checking Adria for a short period of time, but decided it was not interested in the transaction.

The portal added that Adria had been spreading news about an upcoming agreement to buy time and improve its position as well as possible investors' confidence.

Adria then denied the portal's claims, saying "due diligence and negotiations with a potential strategic partner are still under way in the company".

The news comes just weeks after Adria, which was beset by flight delays and cancellations in the first half of the year but appears to have stabilised its operations, announced it was looking for a strategic partner.

Mesa Airlines, a subsidiary of the Mesa Air Group, is confined to the US, operating regional domestic flights for American Airlines and United Airlines under the American Eagle and United Express brands.

It has a fleet of over 140 aircraft, most of them either Bombardier CRJ700 or CRJ900 jets, which also make up the bulk of Adria Airways' fleet, according to aviation industry portal Ex-Yu Aviation News.