The move comes a week after Dassault's parliamentary immunity was lifted. The 88-year-old is suspected of buying votes in Corbeil-Essonnes, east of Paris, where he was formerly mayor.
Dassault himself requested the lifting of his immunity in order to defend himself.
The veteran industrialist was taken into custody and interrogated by the police's anti-corruption and fraud agency, a judicial source said.
But given his age, he could be moved to a Paris hospital if necessary during the 48 hours he can be held under French law.
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The result of the 2008 vote, won by Dassault, was invalidated by the Council of State after the body which oversees public administration discovered a series of payments which could have influenced the outcome of the election.
Bechter has already been charged, as has Cristela de Oliveira, a former official in the mayor's office who is suspected of allocating council flats to families in return for backing Dassault or Bechter.
Investigating judges are focusing on a huge sum of money transferred between France and Lebanon, including one totalling USD 24 million, which they suspect could have been used to buy votes.