Italy's UniCredit has been hit by a €17.4bn ($23bn) lawsuit filed by a group of shareholders in HVB, the German bank it bought 18 months ago, over several internal transactions that were allegedly damaging to HVB's interests.

German daily Handelsblatt reports that the lawsuit, Germany's largest to date, alleges that HVB sold key units, including Bank Austria Creditanstalt and funds arm Activest, to its parent company for significantly less than their market values.