Police investigating the murders of three Britons in the French Alps have released an image of a male motorcyclist they want to speak to.

Saad al-Hilli, 50, from Claygate, Surrey, his 47-year-old dentist wife Ikbal and her elderly mother Suhaila al-Allaf, were murdered on a remote forest road near Lake Annecy in France on September 5 last year. French cyclist Sylvain Mollier was also killed.

Iraqi-born Mr al-Hilli's eldest daughter Zainab was shot and left for dead, but survived. Her four-year-old sister Zeena hid under her mother's corpse and was only discovered eight hours later.

The French Gendarmerie have released an artist's impression of a motorcyclist they are trying to trace, who was seen riding in the area between 3.15pm and 3.40pm on the day the murders took place.

They are appealing for anyone who might recognise the man in the image to come forward.

Benoit Vinnemann, head of the investigation, said: "More than the identikit photo itself, it is the type of helmet that is interesting.

"This is someone who may have done or seen something. He is potentially the perpetrator, but mainly a witness."

Police are also searching for a BMW right-hand four-wheel drive vehicle seen nearby at the time.