Multiple sources with knowledge of the case told AFP that a French investigating magistrate had been mandated to take on the probe, which will notably look at acts committed in the Saudi-led war in Yemen.
An initial investigation had been opened in October 2019 against the prince, who is known as MBZ, after two complaints were filed when he traveled to Paris on an official visit in November 2018.
MBZ -- a close ally of Saudi Arabia's Crown Prince Mohammed bin Salman -- has also built a tight alliance with French President Emmanuel Macron.
Six Yemenis had filed a complaint with a judge specializing in crimes against humanity in Paris.
Their complaint focuses on acts of torture committed in UAE-controlled detention centers on Yemeni territory.
It alleges that MBZ as commander in chief of UAE forces is likely to have provided the "means and orders for these violations to be carried out".
Since March 2015, Saudi Arabia and its allies, including the UAE, have been conducting a bloody military aggression in Yemen, using arms supplied by their Western backers. The aim of the war has been to bring Yemen's former president Abd Rabbuh Mansur Hadi back to power and defeat the Houthi Ansarullah movement.