FRANKFURT (Reuters) - UniCredit CEO Andrea Orcel approached German lender Commerzbank's management earlier on Wednesday inviting the bank to explore merger talks, a source with knowledge of the matter told Reuters.

Italy's UniCredit announced on Wednesday it had bought a 9% stake in Commerzbank.

UniCredit's approach is the strongest indication yet that the Italian lender wants to buy Commerzbank.

A spokesperson for Commerzbank, which said it was holding a board meeting later on Wednesday to discuss UniCredit, neither confirmed not denied an approach had been made. UniCredit was not immediately available to comment.