A German biker was stuck under a car after he crashed into a pick-up truck along a highway in Thailand.

Dieter Kaesmayr, 68, was riding with his girlfriend when they were struck by the rear end of a pick-up truck changing lanes in Chachoengsao province on February 12.

The collision knocked Dieter off his blue Suzuki GSX S750 motorcycle and onto the path of an oncoming car.

Miraculously, he slid beneath the sedan, with the driver stopping in time before the German national could be crushed.

Motorists stopped to lift the car and free the injured biker, while the pick-up truck fled the scene.

Paramedics later arrived to administer first aid to Dieter as he was splayed out on the tarmac. He appeared to be responsive and was promptly rushed to a hospital.

Dieter's girlfriend, who was not named by local media, said they were travelling from Pattaya to Ayutthaya when the back of the pick-up struck their motorcycle.

Onlooker Nattapol Saeng-usa, 30, said the motorcycle and truck crossed paths as they each tried to switch lanes at the same time.

Dieter is recovering from his wounds at a hospital.

Police Lieutenant Thanawat Thongcharoen said officers are investigating the crash to trace the driver of the pickup truck.

The deputy inspector of the Chachoengsao police station said: 'The injured man will be interviewed to establish the cause of the crash. When the truck driver has been interviewed we will check all the evidence. At the moment, we do not know who is responsible for the crash.'