A German shareholder group stepped up Wednesday its battle against Italian bank UniCredit, filing a suit in a German court that demands the reversal of a share transaction, according to dpa. The German group claims that UniCredit's German subsidiary, HypoVereinsbank (HVB), transferred that bank's valuable stake in Vienna-based Bank Austria to the parent at less than full value, disadvantaging minority HVB shareholders. "The suit is an important step to reverse the damage done to HVB by UniCredit," said Thomas Heidel, a German lawyer, leading the move. Legal commentators said UniCredit was likely to challenge Heidel's claim to sue in the name of HVB. UniCredit has become the leading bank in eastern Europe thanks to acquisitions. The Italian bank is also in a clinch with the German shareholders over its squeeze-out bid - an attempt to buy all remaining shares in HVB at a standard price and absorb it into the Italian group.