Commerzbank CEO sees strong investment bank as good fit - source

(Recasts lead with source)

FRANKFURT, March 22 (Reuters) - Commerzbank's chief executive believes a strong and focused investment bank would be a good addition to the lender, according to a person familiar with his thinking on Friday.

The person, speaking on condition of anonymity, revealed Chief Executive Officer Martin Zielke's thinking as Commerzbank talks about a possible merger with Deutsche Bank, which has a sprawling global investment bank.

Separately, Zielke promised employees on Friday a quick decision on whether to go forward with the merger, according to a memo seen by Reuters.

"I can promise you that we will strive to keep this period of uncertainty as short as possible and we will work hard to ensure that a decision is reached soon," Zielke wrote.

Zielke said Commerzbank had a clear idea of how it could develop business in a sensible way. "This is the reason why we are in conversations with Deutsche Bank," he said.

(Reporting by Hans Seidenstuecker Writing by Tom Sims Editing by Edmund Blair and Louise Heavens)