An enormous system of caves, chambers and tunnels lies hidden beneath the Pyramids of Giza, according to a British explorer who claims to have found the lost underworld of the pharaohs.

Populated by bats and venomous spiders, the underground complex was found in the limestone bedrock beneath the pyramid field at Giza.

Collins, who will detail his findings in the book "Beneath the Pyramids" to be published in September, tracked down the entrance to the mysterious underworld after reading the forgotten memoirs of a 19th century diplomat and explorer.