UniCredit's bid for BPM also throws a spanner in the works for Italy's government, which had advanced plans for a merger of BPM with rival Monte dei Paschi di Siena which it saw as strengthening its banking sector without harming competition.

UniCredit SpA has hired Deloitte LLP to advise Italy’s second-biggest bank on its takeover bid for Banco BPM SpA, people familiar with the matter said.

With its plans for Germany's Commerzbank seemingly stalled, UniCredit, Italy's second-largest lender, on Monday launched a bid to buy its rival BPM for 10.1 billion euros ($10.6 billion).