A Chinese silk scroll has set a new French auction record for Chinese art, exciting art collectors and investors in the process.

The 18^th century scroll sold for £18m to an anonymous Hong Kong bidder at the Marc Labarbe auction house in Toulouse on Saturday.

The 24 metre work is believed to have been painted in around 1739 under the Qianlong emperor, the fourth emperor of the Qing dynasty.

The scroll was discovered in a Paris attic, having been looted from China's Forbidden City by French troops in 1900.

An original case for the scroll has been kept by the owners.

The Qianlong emperor in a quiet moment between perusing scrolls

"The case would have added at least another 300,000 euros to the price," Pierre Ansas, the specialist who catalogued the painting, told Bloomberg.

It is one of four scrolls produced around the same time, depicting the military manoeuvres of a 20,000-strong army in the 17^th century.

Of the other scrolls, one was sold by Sotheby's for $£42m in 2008, while another resides at Beijing's Palace Museum.