Three wolves in a zoo outside Paris attacked a 37-year-old woman leaving her fighting for her life, a source familiar with the case and local prosecutors said.

The woman was bitten "on the neck, the calf and the back" at the Thoiry zoo around 40 kilometres (25 miles) west of the French capital, the source familiar with the case told AFP.

Maryvonne Caillibotte, chief prosecutor in Versailles, said the woman's life was in danger.

The woman is believed to have gone out alone for a jog after spending the night with her family in a safari-style lodge at the zoo, which it advertised on its website at between 220 and 760 euros ($235-810) per night.

Lodges in the wolf zone promise "silence, rest and disconnection", according to the zoo's adverts. They offer "a one-of-a-kind, very intimate experience with the arctic wolves you'll be able to see from the living room".

The woman "ended up in the safari zone, which is supposed to be restricted to cars. That's where she was attacked by three wolves," Caillibotte said.

She added that it was not clear "whether she made a mistake or the trail wasn't clearly marked".

First responders got to the scene "very quickly", the wolves were "moved away, then returned to their area," Caillibotte siad.

The source familiar with the case earlier said the woman must have got through "security systems, a trench and an electric fence supposed to keep the animals in".

Police are investigating the incident.

Thoiry zoo was founded in 1968 by Paul de la Panouse, owner of a local chateau that has been in his family since the 16th Century.

He recalled to regional newspaper L'Independant in April how he initially stocked the zoo with a ship loaded with 120 animals brought from Kenya.

De la Panouse sold the zoo to a group of investors in 2018.