German Chancellor Olaf Scholz has voiced concern about a potential "hostile takeover" of Commerzbank, following the announcement that Italy's UniCredit had substantially increased its stake in Germany's second-largest bank.

Scholz issued a warning to UniCredit against any "unfriendly "maneuvers in the wake of the Italian bank's disclosure that it had boosted its shareholding in Commerzbank from 9 percent to 21 percent, making it the largest shareholder ahead of the German state, which owns 12 percent.

The European banking sector, particularly in Germany, was surprised earlier this month when UniCredit revealed it had acquired a 9 percent stake in Commerzbank, and events have now intensified after Andrea Orcel, UniCredit's chief executive, hinted at the possibility of a complete takeover.

"Unfriendly attacks, hostile takeovers are not a good thing for banks, which is why the German government has taken a clear position here," Scholz told Reuters on Monday. "We do not consider this to be an appropriate course of action."

Commerzbank is a lender that "operates successfully" and plays a vital role in the German economy, Scholz added, noting the bank's importance in providing necessary funding to small and medium-sized companies in the country.

In the wake of UniCredit's disclosure on Monday, a government official informed the Financial Times that Berlin "supports the strategy of Commerzbank which is geared toward independence".

"We do not support a takeover and we have informed UniCredit about this," the official said.

In response to Scholz's remarks, Italian Foreign Minister Antonio Tajani told Italian media: "These are private but legitimate initiatives. I do not understand why an Italian company buying from the European market would be a hostile act."

Europe operated on a free market system with established rules, Tajani said. "It seems to me that UniCredit has respected them."