The state-run SOD fund, which manages the sales procedure, said all interested parties that fulfilled the conditions in the invitation to submit expressions of interest were invited to participate in the next phase of the sale process.

SOD has not specified how many investors expressed interest beyond saying at the end of April that the procedure was on schedule and the response of "first-rate strategic and financial investors" was "very good".

It is widely believed Deutsche Telekom is the most serious prospective buyer, through its Hungarian or Croatian subsidiaries.

Telekom currently has a market capitalisation of EUR 956m. Investment firm Alta Invest has recently put the takeover value at just above market price, around EUR 1bn.