The Italian lender moved to boost its Commerzbank stake above 20%, shrugging off German opposition to a possible takeover.

UniCredit is "doing well" to act within the European Union's internal market, Italian Foreign Minister Antonio Tajani told the Class CNBC network on Monday, commenting on the Milan-based bank interest for Germany's Commerzbank.

Italian government officials are growing frustrated at Germany’s opposition to a potential takeover of Commerzbank AG by Milan-based UniCredit Spa, threatening to disrupt the delicate diplomatic relations between Berlin and Rome.