BERLIN (Reuters) - Italian lender UniCredit has reported its planned acquisition of a 29.99% minority stake in Germany's Commerzbank to the German Cartel Office for assessment, a spokesperson for the regulator said on Wednesday.

The application, dated Monday, appears on a list of current merger control proceedings on the office's website.

The German authority has up to one month to decide whether the purchase is problematic in a first-phase assessment procedure.

UniCredit announced an initial 9% stake in Commerzbank in September, angering the Berlin government and the German lender, which has described the move as hostile and unilateral.

The Italian bank has not backed down, however, and it is also awaiting European Central Bank approval for the stake it has built, largely using derivatives.

UniCredit CEO Andrea Orcel has said he wanted to wait until a new government was in place in Berlin after Sunday's election before making an offer for the rest of Commerzbank.

The planned stake reported to the German regulator sits just below the 30% threshold that would trigger a mandatory takeover offer under German rules.

Orcel said this month that a decision on what to do with the Commerzbank stake would be taken in three to five quarters.