More than 30 people who attended an event with motivational speaker Tony Robbins have been treated for burns after Robbins encouraged them to walk on hot coals as a way of conquering their fears.

Five people were taken to a hospital, while the rest were treated at the scene for burns to their feet and lower extremities.

Representatives for Robbins say about 7000 people walked across the coals and only five asked for treatment.

The hot coals were spread outside the Kay Bailey Hutchison Convention Center as part of a four-day Robbins seminar called "Unleash the Power Within."

It's a regular part of some of Robbins' seminars; more than 20 people were treated for foot burns after an event in 2012 in San Jose, California.

The 6-foot-7 Robbins conducts a variety of seminars "which can range from about $1,000 to up to $3,000" and "Unleash the Power Within" is described on his website as "designed to help you unlock and unleash the forces inside that can help you break through any limit."

Those who do the fire walk are instructed to wear pants that can roll up and avoid loose-fitting or long-flowing clothes.

Robbins says on his website that he believes people who perform tasks they once thought unthinkable, such as walking across hot coals, will help them "conquer the other fires of your life with ease."