MILAN (Reuters) - The general manager of Mediobanca said the take-up in Monte dei Paschi di Siena's bid for the merchant bank would reach 80%, making a merger of the two groups inevitable, as he sought to reassure staff on a conference call.

Mediobanca's Francesco Saverio Vinci said MPS - smaller than its target - had paid a significant price for Mediobanca, albeit mostly in shares, meaning it valued the asset it had bought and would strive to preserve it.

Addressing staff in a conference call held on Tuesday evening, Vinci said that, given the 62% ownership threshold MPS had reached so far, the take-up would rise further when the tender period reopens on September 16, with index-tracking funds being forced to cut their exposure.

"With a take-up at 80% it would be hard to keep Mediobanca listed with such a reduced floating share capital, I imagine also the ECB (European Central Bank) would also push in this direction," Vinci said.

"I think a merger is the lesser evil at this point. To imagine a situation in which two banks which are so different, and can achieve few synergies, would not be the best thing for the bank ... a merger is more rational." he said.

Vinci said Mediobanca shareholders would own more than 60% of the combined entity.

"It is positive we don't have overlaps ... we have different clients and operate in different markets, this can be an interesting starting point," he said.

"MPS didn't pay a little to buy Mediobanca. And when you pay dearly for something it means you value what you're buying, and you'll look after it," he added.

He urged staff to reassure customers that the relationships would maintained and said MPS would behave rationally and strive to preserve the role of Mediobanca employees. The bank currently has around 5,500 employees.