Pop star Justin Bieber risked serious injury after taking part in a dangerous skateboard stunt for a pal's video.

The Baby hitmaker shocked fans after posting a clip of him riding a skateboard while holding on to the door of a moving vehicle. A group of pals can be heard laughing as they catch the moment on camera.

Sharing the video on Instagram.com on Saturday (10May14), Bieber wrote "Ridin down fairfax (Los Angeles) lol had a great time", but the stunt has angered some concerned fans.

One wrote, "Justin. Please be careful, this looks So dangerous!!," while another added: "This is stupid. lol. You could get hurt J."