All three shortlisted bidders for loss-making Italian airline Alitalia presented their non-binding offers by the 16 April deadline.
The government did not release details of the bids.
Bidders include Russia's Aeroflot and Alitalia's closest domestic rival Air One.
The third bidding consortium includes US private equity group Texas Pacific Group (TPG), which recently made a EUR3.4 billion (USD4.61 billion) bid for Spanish flag carrier Iberia.
No additional bidders will be allowed to join the state's auction of at least 39.9 per cent of the state-controlled carrier. A winning bidder for this minimum stake would have to launch a full bid for Alitalia under Italian takeover law.