PARIS, Jan 4 (Reuters) - French prosecutors said on Tuesday they had opened a terrorism investigation into an explosion that went off under a French vehicle involved in the Dakar rally in Saudi Arabia. The blast, which seriously injured one of the rally competitors, hit a support vehicle belonging to the French team Sodicars soon after it left its hotel in the Saudi city of Jeddah for the race route, according to accounts from the team and race organisers. Five team members were in the vehicle at the time and one of them - driver Philippe Boutron - sustained serious leg injuries. French newspaper L"Equipe quoted a team-mate as saying the blast ripped through the floor of the vehicle, which then caught fire. Race director David Castera told L"Equipe that the two-week race will continue, and that he had asked Saudi authorities to assign more police to protect the rally. "There"s a big police presence," he was quoted as saying. Boutron has now been med-evacced to France and is in a medically-induced coma at the Percy Military Hospital, near Paris, with his family at his bedside, his team said in a statement. News of the blast emerged at the weekend, but at the time rally organisers and the sports governing body said there was no explanation for what had happened. France"s anti-terrorist prosecutors, in a statement issued on Tuesday, said they had launched a preliminary investigation into a terrorism-motivated assassination attempt. The statement said that the investigation had been entrusted to France"s domestic counter-terrorism agency. Saudi Arabia’s government media office CIC did not immediately respond to a Reuters request for comment. Saudi Arabia was the scene of a series of large-scale militant attacks on Western targets in the 2000s. The attacks subsided since then. But in late 2020, a blast at a World War One remembrance ceremony organized by the French consulate in Jeddah wounded several people, in the first attack with explosives in years to attempt to hit foreigners in the Gulf Arab state. The previous month a Saudi man was arrested after attacking and wounding a security guard at the French consulate in Jeddah. The Dakar, now in its 44th edition, started in 1978 as a race from Paris to the Senegalese capital but moved from Africa to South America for safety reasons in 2009. It has been held entirely in Saudi Arabia since 2020. In March this year, Jeddah"s Corniche race circuit will host a round of the motorsports world"s most prestigious competition, Formula One.