Google Earth has apparently spotted large and unidentified structures in China's Gobi Desert. The satellite images have raised questions over what China could be building in the region, which shares borders with Mongolia and is used for military, space and nuclear programs.

According to The Telegraph, the area in question is close to the headquarters of the country's space program - Jiuquan, Gansu. The location is also close to a nuclear test site China has since abandoned. The sites are believed to be on the border of  Gansu and Xinjiang provinces in northwestern China, less than 100 miles from Jiuquan.

The buildings are believed to be shaped in rectangular and circular forms and there are also formations that appear to be runways for airplanes. The two images on Google Earth show deep rectangular shapes that seem to be a mile long and a tangle of bright white-colored intersecting lines noticeable from space. The other image shows huge concentric circles, with three jets parked at their centre.

An earlier image, taken in 2007, shows a mass of orange blocks, each the size of shipping container, placed in a circle. A recent image, however, shows them to have moved as far as three miles from the original site.

Although the purpose of the huge structure is unknown, some experts believe it might be an optical test range for missiles.

Tim Ripley, a defense expert, told The Telegraph that the structures all had similar grids to the ones used at the U.S.'s secret military base in Nevada, Area 51.

The picture of the circle looks very like a missile test range, with target and instrumentation set out to record weapon effects. The Americans have lots of these in Nevada - Area 51! he said.