A group of conspiracy theorists believe the Earth is hollow - and that superior 'alien' humans, Vikings and Nazis live inside.

Instead of thinking that the world is flat, they are convinced that it actually contains a paradise at its core that resembles the Garden of Eden.

The 'hollow-Earthers' even believe UFOs are sent from the globe's interior by 'guardians of the planet' to spy on the human race and avert a potential nuclear war.

Author Rodney Cluff is spearheading the bizarre movement which he claims has thousands of followers after a boom in numbers.

Pictured: Author Rodney Cluff, who is spearheading the bizarre movement and insists it is growing in numbers

Cluff is convinced that an inner paradise with its own solar system exists. They believe the same about the moon and other planets (stock illustration)

Cluff told the Sun: 'I don't know how the flat-Earthers can be so confused. They are obviously wrong. The world is not flat – it's hollow.' This ancient map shows a supposed entrance to the hollow Earth

He is so confident in his theory that he organised a voyage to the hollow Earth in 2007 via an 'opening' in the North Pole.

Although the £15,000-per-head expedition was cancelled, Cluff is convinced that an inner paradise with its own solar system exists. They believe the same about the moon and other planets.

The conspiracy theorists believe there is another portal in the poles and one in the Himalayas - leading to a land that is home to immortal escaped Nazis from World War II and the lost Viking colonies.

The conspiracy theorists believe there are two portals in the poles and one in the Himalayas - leading to a land that is home to immortal escaped Nazis from World War II and lost Vikings (stock illustration)

Instead of thinking that the world is flat, the conspiracists are convinced that it actually contains a paradise at its core that resembles the Garden of Eden (stock illustration)

Cluff told the Sun: 'I don't know how the flat-Earthers can be so confused. They are obviously wrong. The world is not flat – it's hollow.'

He continued: 'They regularly spy on us using spacecrafts and flying saucers.

'They want to keep an eye on us and stop us from starting nuclear war. The majority of UFOs actually come from inside our planet.'

In 1811, a Norwegian sailor named Olaf Jansen claimed he had sailed through an entrance to the inside of Earth at the North Pole.

He claimed to have lived in the beautiful paradise for years with his father - among humans who were 12 feet tall and immune from illness.

Jansen told author Willis George Emerson: 'The city of 'Eden' is located in what seems to be a beautiful valley, yet, in fact, it is on the loftiest mountain plateau of the Inner Continent.'

The theories have all been completely rubbished by modern science.