A man has been arrested over the murder of three members of his family and a cyclist who were shot dead in the Alps, according to reports.

Zaid al Hilli, 54, was held by Surrey Police in Britain, who have been investigating the deaths of husband and wife Saad and Ikbal al Hilli, Mrs al Hilli's mother Suhaila al Allaf and cyclist Sylvain Mollier. The suspect - Saad al Hilli's brother - was arrested on suspicion of conspiracy to commit murder at an address in Chessington at around 7.30am, police said.

Surrey Police said the arrest was pre-planned and the result of on-going inquiries. The four victims were gunned down near Annecy in the French Alps in September last year.

The couple's two young daughters, aged 7 and 4 at the time, survived the attack on the family's estate car. Older sibling Zainab was shot in the shoulder and hit in the head by her attacker, but recovered from her injuries. Her 4-year-old sister Zeena survived by hiding under her mother's skirt in the back seat of the vehicle and was only found by police eight hours later.

Police believe Mr. Mollier was an innocent bystander, killed because he was passing at the time of the attack on the family. Surrey Police set up a Joint Investigation Team to work with their French colleagues with up to 100 officers working on the case.

In May, Surrey Police issued an appeal for help to trace a vehicle, thought to be UK-registered, which was seen near the crime scene. Detectives said the 4x4 was being driven on the Combre d'Ire Road in Chevaline, near Annecy, about 20 minutes before the shooting.