France's convoluted L'Oréal family fraud scandal became even more convoluted and even more gripping yesterday. Tapes of bugged conversations involving the L'Oréal owner, Liliane Bettencourt, 87, implied that President Nicolas Sarkozy had meddled in legal proceedings in which a society photographer is accused of defrauding France's richest woman of almost a billion euros.

The tapes, leaked to a French investigative website, also suggest that the supposedly senile billionairess was involved in elaborate schemes to hide some of her money abroad. There are cryptic references to campaign payments to ensure the "friendship" of two cabinet ministers, including the employment minister, Eric Woerth.

Ms Bettencourt's former butler was arrested yesterday and faces charges of "invasion of privacy", for allegedly bugging conversations between the L'Oréal heiress and her financial adviser. He has not been named. Tapes of the conversations were sent last week to Ms Bettencourt's only daughter, Françoise, who sent them to the police.

Françoise Bettencourt-Meyers brought a legal action last year for fraud and abuse of "weakness" of mind against François-Marie Banier, 54, a jet-set photographer who befriended her mother 15 years ago. The case, in which Mr Banier is accused of receiving almost €1bn in cash, paintings and life insurance policies from the elderly woman, will be heard in two weeks' time.

A former butler of Ms Bettencourt is alleged to have secretly made the tapes over the last year in an act of revenge, after she fired other staff members who cooperated with investigators. Ms Bettencourt-Meyers' lawyer, Olivier Metzner – a star of the French bar, also involved in the case of the trader Jerome Kerviel – has rejected suggestions that the bugging was carried out at the request of Mrs Bettencourt's daughter. She received the tapes anonymously, he said, and immediately gave them to the police.

The tapes are of conversations over the last 12 months between Ms Bettencourt and her financial adviser, Patrice de Maistre. In one tape, allegedly recorded in April this year, he tells her that he recently met President Sarkozy's legal adviser, Patrick Ouart. Mr Sarkozy is a friend of the Bettencourt family and a former mayor of Neuilly-sur-Seine, the wealthy ghetto on the western border of Paris where both mother and daughter live.

"[Ouart] wanted to see me the other day and he said 'M de Maistre, the President is continuing to follow [the Bettencourt trial] very closely. In the first hearing, there is nothing more we can do, but if you lose and it goes to appeal, we know the chief prosecutor very, very well.'"

In another bugged conversation, Mr de Maistre urges the billionairess to give campaign contributions of the €7,000 maximum to two cabinet ministers because "we need friends". One of the ministers is Mr Woerth, whose wife works in Ms Bettencourt's private office. The minister denied any knowledge of the payment yesterday but said that "anyone" could contribute to his campaign funds.

At the end of the taped conversation about campaign payments, Ms Bettencourt asks: "And Nicolas Sarkozy?" Her financial adviser replies: "That's taken care of. He knows about it."