The Portuguese government is studying improved offers from two bidders for the heavily-indebted national airline TAP Portugal.

Transport Secretary Sergio Monteiro said late Friday he hoped the two consortiums had "significantly improved their proposals."

Portugal announced last month it will consider bids for 61 percent of the state-owned airline from German Efromovich, owner of Colombian airline Avianca, and from David Neeleman, who founded Brazil's third-largest airline Azul.

But Portugal said Tuesday that the bids needed to be improved, hinting that otherwise the sale could be called off. The financial terms weren't revealed.

The government hopes to complete the sale, which would recapitalize the airline so it can modernize its fleet, by the end of June though the deal would require regulators' consent, which might take months.