In an interview with state TV broadcaster RTS aired on Sunday, Marzouki said the money was “stolen from the Tunisian people”.
Marzouki, in Geneva for a meeting of the United Nations Human Rights Council, called on Switzerland to help in recuperating the cash.
“We have spoken of 60 million but it is probably 10 times more,” Marzouki said of the amount stashed in accounts by Ali’s entourage.
He said he regretted that the Swiss government had lifted a freeze on some of the relevant accounts because they belonged to “major gangsters” in league with the “corrupt” Ben Ali regime.
Ben Ali was forced to flee to Saudi Arabia in early 2011 with his wife and three children after a month of protests against his rule.
A Tunisian court later sentenced him in absentia to 35 years in prison on charges of theft and unlawful possession of cash and jewellery.
He has also been sentenced to life in prison under other rulings from two courts in Tunisia for inciting violence and murder and for violent repression of protests.
Marzouki came into power after the “Arab spring” revolution that led to Ben Ali’s departure from Tunisia.
Commenting in the RTS interview on Tunisian asylum seekers in Switzerland, he said: “There is no longer a political reason, there are only economic reasons.”
He added that in Tunisia there is total freedom of expression and association, so there was no reason for the numerous requests for asylum in Switzerland from Tunisians.
Marzouki in December asked the Swiss federal government to review a decision to extend a freeze for three years on 60 million francs in bank accounts held by Ben Ali.