Italy’s UniCredit moved to buy another big chunk of Commerzbank, shrugging off German opposition to a possible takeover and upping the ante in its attempt to create a European banking champion with nearly $1.

UniCredit SpA Chief Executive Officer Andrea Orcel used Barclays Plc to help quietly build up a stake in Commerzbank AG, a move that has shaken European finance and triggered a backlash from the German government.

UniCredit on Monday said it’s reached an agreement to further increase its stake in Commerzbank as the German government increasingly attempts to ward off an Italian acquisition of its number-two bank.