French police have been searching the home of Francoise Bettencourt-Meyers, the daughter of the L'Oreal heiress Liliane Bettencourt, France's richest woman.

What began as a family feud over lavish gifts by Bettencourt to a close friend, society photographer Francois-Marie Banier, has turned into a political scandal.

Investigators are trying to clarify Francoise Meyers-Bettencourt's role into secret recordings made by a butler at her mother's home and how they reached judicial authorities and the media.

But her lawyer, Olivier Metzner, said there was nothing new to be found: "They took documents which, for the main part, had already been given to the judges, they took some diaries, their mission was fruitless because there was nothing to be found. Furthermore, Francoise Bettencourt has nothing to hide."

The billionairess's daughter, Francoise Meyers-Bettencourt, filed two lawsuits seeking to have her mother declared mentally unfit and made a ward of the court.

The recordings sparked a scandal which is rocking president Sarkozy's government as police are also investigating whether L'Oreal heiress Liliane Bettencourt and her late husband made illegal campaign donations to conservative politicians. The inquiry was ordered after the former bookkeeper of Liliane Bettencourt alleged she had routinely withdrawn cash destined for illegal donations.

She alleged that 50,000 euros was added to cash from Switzerland and given to Labour Minister Eric Woerth, treasurer of the ruling centre-right UMP party. Woerth has denied receiving any illegal money and rejected accusations of a conflict of interest over his wife's job with Bettencourt's wealth manager while he was budget minister in charge of tax affairs and treasurer of the UMP party.

He is expected to be questioned by police later this week.