MILAN, July 17 (Reuters) - Spanish fund Asterion will invest in Italian airports after agreeing to buy 49% of a holding company that controls the Naples and Turin airports among other from France's Ardian and Credit Agricole Assurance, sources close to the matter said.

An official announcement for the deal is expected later on Wednesday, according to the sources. (Reporting by Elisa Anzolin; writing by Valentina Za; editing by Alessandro Parodi)