BERLIN (Reuters) - Commerzbank's supervisory board chairman Jens Weidmann said there is little chance for an amicable merger with UniCredit after the Italian bank's surprise purchase of a hefty stake in the German lender, Handelsblatt newspaper reported.

"It's like any relationship: if the start is unsuccessful, it will be difficult," Weidmann told Handelsblatt in an interview published on Monday.

He also expressed doubt that a hostile takeover in the banking sector can create sustainable value.

"In mergers, it is important that the management first talks to each other in a spirit of trust and develops a common understanding. UniCredit has decided against this and surprised us with its entry. That's not good style," Weidmann said.

UniCredit now controls around 28% of the shares in Commerzbank. The Italian lender holds about 9.5% directly, and UniCredit has also secured access to a total of 18.5% through financial instruments.

According to Weidmann, it would be advantageous for Germany's financial sovereignty to have two large independent private banks, Deutsche Bank and Commerzbank.

A look at HypoVereinsbank and Bank Austria, which were taken over by UniCredit in 2005, shows how banks can evolve after losing their independence, he said.

"Commerzbank's footprint in Germany would probably be smaller and the attractiveness of Frankfurt as a financial centre would suffer," said Weidmann, adding that many customers, especially from the small and medium-sized enterprise sector, would be forced to reorient themselves in response to such a move.

(Writing by Miranda Murray; Editing by Jamie Freed)