The row comes after Fincantieri won an E300m ($372m) order from Finland's Finnlines for three super ro-pax ferries last month with an option for two more at E100m each.
The ships will enter service between Finland and Germany in 2005-6 and will be the biggest and fastest of their type.
Unconfirmed stories in the Finnish media this week said Finland's Ministry of Trade and Industry was seeking an investigation into a number of contracts won by the Italian shipbuilder at the apparent expense of Finnish yards.
