Four Italians have constructed what they believe is the world’s first full-sized chocolate igloo but they have yet to solve an age-old problem. It still melts.

"It was a tough thing to do, much more difficult than building a normal snow igloo," Marco Fanti, 45, who used to race cars in desert rallies, told Reuters as he stood beside the 1.65-metre-high, dome-shaped traditional Inuit shelter made of some 330 dark chocolate bricks.

Fanti and fellow instructors at a survival school took 23 hours working with tricky, crumbling chocolate material to construct what they believe to be the world’s first chocolate igloo for the Eurochocolate fair in Perugia.

They normally build one made of snow, for survival courses, within three to four hours.

Fanti said it has yet to be decided what to do with the 3.6- tonne igloo — which is kept indoors and will start melting at above 30 C — when the fair ends on Oct 22.