Under Swiss law, Tunisia's new unity government would have to launch its own criminal investigation and request judicial assistance for Switzerland to cooperate, Swiss officials say.
Although Tunisian authorities had not asked their Swiss counterparts to freeze any accounts for now, the Conseil Federal (federal cabinet) could decide to do so at its weekly meeting on Wednesday to prevent funds leaving the country.
In recent years, Switzerland has worked hard to improve its image as a haven for ill-gotten assets.
The cabinet has taken unilateral measures to block funds in Swiss accounts held by deposed dictators including Ferdinand Marcos, Nigeria's Sani Abacha and Haiti's
Francois "Papa Doc" Duvalier, buying time for foreign prosecutors to build a case for restitution of funds.
The Berne-based prosecutor's office "received two criminal complaints on Jan. 17 related to the freezing of Tunisian assets which might have been deposited in
Switzerland by the family or close associates of President Ben Ali", the federal prosecutor's spokeswoman Walburga Bur said.
"We are examining the complaints," she said by email.
Another spokeswoman, Jeannette Balmer, said that there was no formal legal investigation at this point, but the allegations were being examined. She declined to provide any details.
Weeks of protests against poverty and unemployment in Tunisia forced Ben Ali from office after 23 years on Friday. Tunisian police used teargas on Tuesday to break up a protest against a new coalition government that includes allies of the ousted leader, who went to Saudi Arabia.
An association of Tunisians living in Switzerland lodged one of the complaints, a Swiss judicial source said. It sought the freezing of assets including a building on Geneva's exclusive rue du Rhone and a Falcon 9000 jet said to be at Geneva airport.
Swiss banks have an obligation to carry out 'due diligence' to know their customers and the origin of their funds, or they can face financial and criminal sanctions.
"Swiss banks have drawn the lesson from Abachi, they have learned to separate the wheat from the chaff," a Swiss judicial source who declined to be named told Reuters. "They are obliged to flag any accounts or files that look fishy."
"You can be sure banks in Switzerland are in the process of frenetically going over their accounts and seeing what holds up and what is suspect," he added.