The Italian ministry of the economy and finance has invited expressions of interest for the purchase of shareholding of not less than 30.1% in Alitalia, and all the Alitalia convertible bonds owned by the ministry.According to agency reports, the potential buyers must guarantee the airline's 18,000 jobs, national routes, and the Italian identity of the Alitalia brand.The ministry, in a document published on its website (www.mef.govt.it), said expressions of interest for Alitalia must be presented by January 29.