italian lender UniCredit BankGerman Finance Minister Jörg Kukies criticized Commerzbank's "very aggressive, very opaque" takeover of Commerzbank, stressing that hostile takeovers usually don't work.

"In government, we need to protect the safety and stability of systemic banking," Kukis told CNBC on Thursday at the World Economic Forum in Davos. "Hostile takeovers of systemic banks tend not to succeed."

UniCredit now owns 9.5% of Commerzbank directly and 18.5% through derivatives after a surprise stake increase in September and subsequent increases in stake.

The Italian bank, which had a CET1 ratio - a measure of a bank's strength and resilience - as high as 16.1% as of the third quarter, is seeking permission from the European Central Bank, which oversees the euro zone's largest banks, to increase its stake in Commerzbank to 29.99 %.

UniCredit's suddenly accelerated pace of acquisitions has fueled speculation that CEO Andrea Orcel, a veteran Merrill Lynch dealmaker, is ultimately targeting cross-border integration.

UniCredit already has a presence in Germany through its HypoVereinsbank branch, but its moves have so far been met with a cold reception by the fractured Berlin government, with outgoing Chancellor Olaf Scholz criticizing, "No. Friendly attacks, hostile takeovers are not a good thing for banks."

Divisive domestic politics in December and upcoming elections could prevent the German government from closely managing the deal.

"In this specific case, the potential acquirer acted very aggressively, very opaquely, very opaquely," Kukis told CNBC's Karen Tso and Steve Sedgwick. "Hostile takeovers are not a good thing for systemic banks. So it all depends on the specific circumstances of this case and this is not a general statement that Germany is not open to business with global investors."

CNBC has reached out to UniCredit for comment.

Last November, just months after it unexpectedly increased its stake, Orcel noted in an interview with CNBC: "Let's put it this way: If we hadn't been invited to buy these shares, we wouldn't be here. All of this It all starts in a way that we think is constructive."

In late November, the Italian banking group simultaneously launched an ambitious formal takeover bid for Italian peer Banco BPM, raising questions about its commitment to the deal.

Commerzbank, for its part, has argued for acting independently, with one board member warning that the integration would lead to massive job losses if the two banks merged.

Europe's interest in cross-border consolidation has waned since the controversy that followed Dutch bank ABN Amro's acquisition and subsequent carve-up in 2007 by a consortium led by Royal Bank of Scotland, which ultimately led to the bank's financial Closure during crisis. UniCredit's Ossel, then a senior investment banker at Merrill Lynch, advised on the deal.

Yet analysts say banking consolidation in the region, particularly in Germany, is "long overdue." Commerzbank had previously been a takeover target by Deutsche Bank, the country's largest bank, before preliminary talks suddenly collapsed in 2019.

"The suggestion that there is no consolidation and no change in the German banking sector is absolutely wrong," Kukis said on Thursday.

UniCredit and Commerzbank will release fourth-quarter results on February 10 and February 13 respectively.