FRANKFURT/MILAN, March 16 (Reuters) - Italian bank UniCredit said on Monday it was launching an offer to own more than 30% of Commerzbank, crossing the mandatory takeover threshold existing under German law.

UniCredit said it did not expect to reach control of the German peer of which it owns 26% in equity and another 4% through total return swap contracts.

"It is expected that UniCredit will achieve a stake in Commerzbank in excess of 30% without reaching control," UniCredit said in a statement.

"The offer is designed to overcome the 30% cliff-edge that exists under German takeover law and foster constructive engagement with Commerzbank and its stakeholders in the coming weeks," it added.

Under German rules the markets authority will determine the price of the offer, UniCredit said, adding it expected it to be set at 0.485 shares of UniCredit per share of Commerzbank. This would imply a 30.8 euro price per Commerzbank share, or a 4% premium on the German bank's closing price on March 13.