Frenchman Romain Vandendorpe on Saturday set a world record for sitting immersed in ice cubes for the longest time, enduring the extreme challenge to raise money for childhood cancers.

The 34-year-old health worker remained buried up to his neck in ice in a plexiglass cabin for two hours, 35 minutes and 43 seconds, breaking the previous record by 40 minutes in the northern French town of Wattrelos.

He said he trained to "overcome human limits" by neuro-cognitive techniques based on "imagination and concentration" to put himself in "a state of daydreaming."

The feat was performed before some 50 people and Vandendorpe's mantra for success was simple.

His training techniques included sitting in an ice-cold jacuzzi, training in a 500-litre freezer and then remaining buried in snow in the French ski resort of Chamonix.

He aims to donate the money raised through his feat to the Wonder Augustine association. The charity is named after a four-year-old girl who died two years ago from brain cancer.

Vandendorpe had met Augustine a few days before her passing.