At least eight of a group of amateur cyclists have been killed an four others injured after being hit by a car speeding out of control in southern Italy, police say.

An investigation into the accident showed the vehicle ran headfirst into the group of cyclists, who were riding in the opposite direction on a highway in the city of Lamezia Terme in Calabria region, according to highway authorities.

Umberto Perri, a local police official, said two of the cyclists were airlifted by helicopter to local hospitals.

Another police official, Nicola Ottocalli, told Sky TG24, the Italian news channel, that one of those taken to a hospital later died.

The ANSA news agency said the driver was trying to pass another car when he hit the group. Visibility and driving conditions were good at the time, reports said.

ANSA said the driver, who was injured in the collision, was placed under arrest.

A police spokesman said the man, a Moroccan national, had tested positive for marijuana following the accident.

It is common in Italy to see groups of cyclists taking to small state roads for leisure on weekends.