French budget minister Jerome Cahuzac has resigned after coming under pressure over claims that he once had an illegal Swiss bank account.
President Francois Hollande's office said Cahuzac had asked to be removed from his post after a scandal over suspected tax fraud and money laundering. Europe minister Bernard Cazeneuve was named as his successor.
The outgoing minister has denied a December report by French investigative website Mediaparte which claimed to have evidence that he held an undisclosed account at the Swiss bank UBS until the start of 2010.
Prosecutors in Paris launched a judicial probe into the case.
They claimed that lab tests on a phone conversation between an unnamed man who admitted to holding an unauthorised account at UBS and a Mediaparte journalist proved that the man was Cahuzac.
"In other words, the result of our analysis reinforces the hypothesis that Jerome Cahuzac is the unidentified speaker," the office of the Paris prosecutor said.
Cahuzac has long been a vocal crusader against use of overseas tax havens.