Paris, France (CNN) -- French police on Friday raided two locations linked to L'Oreal heiress Liliane Bettencourt as part of an investigation into allegations she secretly funded President Nicolas Sarkozy's election campaign.
Police were seen at the home of Bettencourt's financial adviser, Patrice de Maistre, and at the offices of the Clymene company, which manages Bettencourt's family fortune.
Police also questioned Bettencourt's former bookkeeper, Claire Thibout, overnight. Thibout alleged in an interview this week that Sarkozy's party, the UMP, received illegal campaign donations in cash from the heiress and her late husband in 2007.
Thibout told the French investigative website Mediapart, in an interview published Tuesday, that the campaign received 150,000 euros (nearly $190,000 U.S.) in cash from the Bettencourts, well above the 7,500-euro (about $9,500) limit permitted for donations to political parties.
She said she had personally withdrawn 50,000 euros (about $63,000) from a Bettencourt account sometime in the spring of 2007 at de Maistre's request. The money went to the campaign, via current Labor Minister Eric Woerth, she said.
Sarkozy also received envelopes of cash personally while he was mayor of Neuilly-Sur-Seine between 1983 and 2002, Thibout said in the interview.
Sarkozy's office and Woerth denied the allegations, but French prosecutors opened a preliminary investigation into the matter a day later.
Woerth also filed an official complaint for "malicious falsehood" over the allegations.
The investigation, and the allegations that sparked them, come on the sidelines of a high-profile trial in Paris involving Bettencourt, who is France's richest woman.
The heiress's daughter accuses a photographer, Francois-Marie Banier, of bilking the 87-year-old Bettencourt out of a billion euros that she allegedly gave to him. The daughter says her mother is not mentally competent to handle her own affairs and took the case to court to recover the money.
Bettencourt and Banier have known each other for years.
The trial is on hold while officials investigate secret recordings that emerged last month on the Mediapart website. Allegedly made by Bettencourt's butler, the recordings capture Bettencourt talking to de Maistre about secret money and payments.
The two are heard discussing a bank account in Switzerland containing 80 million euros (about $100 million) that had not been reported on Bettencourt's taxes. They also refer to payments to two ministers in Sarkozy's government, including Woerth.
The tapes revealed that Woerth's wife was, until late June, the deputy to Bettencourt's financial adviser.
Banier would face up to three years in prison and a 75,000 euro (nearly $95,000) fine if he's convicted at the trial, which is being held at a court in the Paris suburb of Nanterre.
CNN's Saskya Vandoorne contributed to this report.