The mysterious clouds were seen on the morning of Sunday above a barracks and last for about an hour
A mysterious cloud formation was spotted floating over northwest China's Yanqi Basin yesterday.

Residents in the area noticed the colourful cloud in the morning, describing it as a 'huge question mark hanging in the northern sky,' reports The People's Daily Online.

Pictures of the unusual phenomenon have sent the Chinese online community into overdrive with many speculating what the shadowy object could be.

According to some witnesses the colourful smoke-like clouds were spotted at around 7:55am above a barracks based in the region.

The photos were taken by a group of 20 migrant workers who were staying in the basin.

The workers said the mysterious object seemed to get bigger the higher it floated into the sky. It gradually changed its shape to an irregular curve, eventually disappearing at around 9am.

One of the eyewitnesses recalled seeing something similar in the 1970's.

Many people in China have been saying the mysterious cloud looks like a questions mark in the sky.
It remains unknown where the cloud had come from or what could have caused the formation, but Chinese web users are keen to give their own interpretations.

Some are saying it's a UFO or an alien. Others think it could be a plane or even the smoke from fireworks set off in the area.

This not the first time a mysterious object has been spotted floating over China in recent months.

In October, thousands of people claimed they saw a floating city in the sky.

Residents of Jiangxi and Foshan in southern China were stunned when they saw what they thought to be towering sky scrapers appearing from the clouds.

While many believed they had seen a parallel universes. Weather experts said the phenomenon was down to an optical illusion known as a Fata Morgana.