Buenos Aires  - Qatari Nasser al-Attiyah won the sixth stage of the Dakar Rally on Thursday to increase his overall lead.

However the BMW X3 driver could face a time penalty after a review of whether he went through all the control points on a shortened 178-kilometre stage between San Rafael and Mendoza in Argentina.

Al-Attiyah of the X-Raid team posted 2 hours 7 minutes 26 seconds to finish ahead 5:07 ahead of Giniel de Villiers of South Africa in a Volkswagen Touareg.

He was followed by two more VWs driven by Mark Miller of the United States and Carlos Sainz of Spain, with Stephane Peterhansel of France fifth in the first of the Mitsubishis.

If the times are confirmed, al-Attiyah now has a lead of 7 minutes 31 seconds over de Villers and 15:10 over Sainz.

In the motorcycle event, Cyril Despres of France won his first stage victory of the race, ahead of Spain's Marc Coma who increased his overall lead to 40:29 over Jonah Street of the United States.

Organizers reduced the day's timed section after impassable river ford forced them to shorten the route.

Meanwhile there was criticism of the organizers over the death of French motorcyclist Pascal Terry, with authorities saying he could have been saved if he had been discovered earlier.

The 49-year-old Yamaha rider had gone missing during the second stage between Santa Rosa and Puerto Madryn in the province of Chubut on Sunday.

His body was found in the early hours of Wednesday about 15 metres from his bike around 300 metres from the stage route.

Police official Julio Acosta told the Telam news agency: "He could have been saved if he had been rescued in time and if we had been alerted sufficiently in advance to begin our search."

Acosta said Terry "died of a pulmonary oedema, which caused a respiratory and cardiac arrest."

Etienne Lavigne, director of the Dakar rally, said that an internal malfunction at the Amaury Sports Organization, which organizes the event, was responsible for the search beginning too late.

French daily Liberation quoted Lavigne as saying, "There was a problem in the chain of communication."

Liberation says that as a result 12 hours were lost before the search for Terry began.

In addition, because they believed, erroneously, that Terry had been seen in Neuquen, the finish of the fourth stage, the search was interrupted for several hours.

Local police and justice officials have opened an investigation into Terry's death. (dpa)