PARIS (AP) — The Paris prosecutor's office says it has opened a preliminary investigation into scarf and bag maker Hermes' claim that luxury giant LVMH Moet Hennessy Louis Vuitton engaged in insider trading and share manipulation when it took a stake in its rival.

The French stock market regulator AMF is already looking into LVMH's 2010 acquisition of Hermes stock, but Hermes has also filed a criminal complaint. LVMH has called the charges completely unfounded and an attempt to slander a competitor.

The prosecutor's office confirmed Friday that it is investigating.

LVMH initially bought a 14.2 percent stake in Hermes in October 2010, to the apparent dismay of the Hermes family, which called the move "unsolicited" and vowed to maintain its independence. LVMH has since increased its stake to 22.3 percent.