Conspiracy theorists claim to have found evidence of ‘ancient walled cities’ on Mars in their latest bizarre theory.

The United Family of Anomaly Hunters, a group of UFO hunters, presented the evidence in a YouTube video.

The video shows a series of aerial Nasa pictures of Elysium Planitia is a plain near the Martian equator.

The images show a number of aerial views, some of which look like eroded domes that could be surrounded by virtually circular rings.

The ring and cone structures were spotted on Elysium Planitia, a plain near the Martian equator.

The title of the video, ‘Nasa Spots Walled Cities on Mars from MRO Satellite’, implies Nasa has claimed these structures are walled cities.

The video has been met with mixed reaction – some firmly believed the structures show signs of life.

‘There are structures similar to these all over certain areas in South Africa,’ one user said.

‘I firmly believe Mars still has some remnants of it’s civilisation living underground,’ said another.

While others put it down to natural geological processes.

The images show a number of aerial views, some of which look like eroded domes that could be surrounded by virtually circular rings

‘You should change your channel’s name to “Martian Geology,” because that’s what were actually looking at,’ one commenter said.

The images were taken by Nasa’s Mars Reconnaissance Orbiter (MRO).

The Mars Reconnaissance Orbiter has been circling the red planet, capturing pictures using its High Resolution Imaging Science Experiment (HiRISE) camera, since 2006.

Mars is now a frozen desert, but geological studies of rocks by previous missions to the surface have suggested the planet used to be warmer and wetter.

Elysium Planitia is a plain near the Martian equator.

Previously, ESA has released an image of the plain, showing what looks like a dust-covered frozen sea.