A video of a cyclist holding the back of a trailer traveling at highway speeds on a motorway near Cairns, Queensland, has gone viral.

Police are searching for the cyclist - to remind him of the dangers of his actions.

The video was uploaded by a Facebook user named Angela Scott, which was later uploaded again by 7News Brisbane. Scott was following the trailer on the highway when he saw the man on his bike using his right hand to hold on to the back of a fast-moving trailer.

Scott said she followed the man on the bike, who held on to the trailer for approximately 3 kilometers. Scott wrote "Crazy Dude!" on the caption of her original post.

Local police condemned the act and said the stunt not only put the man's life at risk but also other motorists.

Facebook users said hitching a ride on vehicles moving at highway speeds was extremely dangerous as "speed wobble" could occur and the cyclist could be seriously injured if he crashed.

There is also the possibility of him getting run over by another vehicle or causing a big accident on the highway.

While there may be no law that says hitching a lift on the back of a moving vehicle is illegal, police have asked the public to refrain from dangerous stunts.

Police reminded the public to use highways with care and to be considerate to other motorists.