French investigators probing an explosion that badly wounded a driver at the Dakar Rally in Saudi Arabia have concluded an improvised explosive device caused it, a source close to the investigation revealed on Friday.

Investigators from France's specialized anti-terror prosecutor's office visited the country after the blast and analyzed the damaged car alongside police and domestic intelligence agency officers, the source told AFP, speaking on condition of anonymity.

The December 30 blast damaged a support team car driven by 61-year-old Philippe Boutron near a hotel in the city of Jeddah. Four other French people in the vehicle escaped unharmed.

The Saudi Interior Ministry initially claimed there was "no criminal suspicion in the accident," but French authorities quickly raised suspicions that the blast was a "terror attack" and investigators were brought in.

One of the unharmed passengers, Thierry Richard, told AFP afterward he had no doubt the car had been targeted deliberately, saying, "It was an attack, they blew us up." 

The race -- formerly called the Paris-Dakar and now known just as The Dakar -- used to be staged from the French capital along a route to the Senegalese capital Dakar.

But the security threats in North Africa starting in 2009 shifted the race to South America and from 2020 to Saudi Arabia.