(CNN) -- French Labor Minister Eric Woerth is being questioned by police in connection with their investigation into the finances of L'Oreal heiress Liliane Bettencourt, the prosecutor's office in Nanterre, France, said Thursday.
Police are investigating claims that Bettencourt's adviser gave envelopes of cash to French President Nicolas Sarkozy and Woerth.
Woerth and Sarkozy have both denied the allegations, which resulted from secret recordings that surfaced last month.
The recordings, allegedly made by Bettencourt's butler, also refer to a bank account in Switzerland containing 80 million euros ($98.3 million), which had not been reported on Bettencourt's taxes.
Woerth's wife, Florence, was questioned last week, the spokeswoman said.
The secret recordings published last month revealed that Florence Woerth was, until late June, the deputy to Bettencourt's financial adviser, Patrice de Maistre.
Bettencourt's former bookkeeper, Claire Thibout, elaborated on the allegations in an interview this month with a French investigative website.
She said she prepared envelopes of cash that were to be given to Sarkozy and Woerth, who previously worked in the Budget Ministry and was in charge of reforms to France's retirement system.
Thibout's lawyer told French news agency Agence France-Presse this month that de Maistre once asked his client for 150,000 euros ($188,800) and said he would give it "discreetly" to Woerth at a dinner.
Thibout testified before a judge about the allegations earlier in July.
The French newspaper Le Monde published her testimony, in which she repeated her allegations against de Maistre and said she regularly withdrew large sums of money at his request.
Among other claims is that Sarkozy's 2007 presidential campaign received money from Bettencourt in excess of campaign finance limits.