Lufthansa sees a need for "significant" restructuring at Italy's Alitalia before the German airline can make a deal to buy the carrier, according to a letter by Lufthansa chief executive Carsten Spohr seen by Reuters on Thursday.

"While recognising the valuable measures that have been undertaken to date under the leadership of the commissioners, we strongly believe that there remains a considerable amount of work to be achieved before Lufthansa would be in the position to enter comprehensively into the next phase of the process," Spohr said in the letter to Italian Industry Minister Carlo Calenda.

He said restructured "NewAlitalia" would be smaller in terms of both staff and its fleet.

Alitalia, which has made a profit only a few times in its 70-year history, was put under special administration last year after staff rejected a plan to cut jobs and salaries.

Lufthansa, British low-cost carrier easyJet and US private equity fund Cerberus are among companies that have expressed an interest in Alitalia.