The Greek government, which bought the aircraft from former state carrier Olympic Air in 1999, decided to sell them in 2014 but the process has been delayed because it failed to transfer the assets to HRADF.

HRADF said the tender would take place in one phase on condition that Greece concluded the transfer of the property before the transaction was wrapped up.

The agency said the timely conclusion of the sale was imperative due to the high maintenance and parking costs of the aircraft, and their continuing depreciation.

HRADF did not say how much it could raise from the sale. It set an April 11 deadline to investors to submit binding offers and expected to conclude the sale in June.

Privatisations have been a key part of Greece's bailout programmes since 2010 but have produced very poor revenues so far due to bureaucracy and political resistance.

(Reporting by Angeliki Koutantou; Editing by Mark Potter)