China is to send a team of artefact hunters to nearly 50 countries to track down thousands of treasures looted by foreign armies 150 years ago.

The experts will scour museums, libraries and private collections in Britain, the US, France, Japan and elsewhere to photograph and catalogue what was taken from the Yuan Ming Yuan, popularly known as the Old Summer Palace, after British and French armies sacked it in 1860 then picked through what remained in 1900.

Chen Mingjie, the director of Yuan Ming Yuan, said: “We hope to build a complete database of the Old Summer Palace’s lost relics so we can have a clearer view of the historical royal garden, then known as the Garden of Gardens, before it was looted and burnt.”

He was not sure how many treasures had been pillaged from the palace, which was a summer pleasure ground for Chinese emperors in the 18th and 19th centuries. “Based on our rough calculations, about 1.5 million relics are housed in more than 2,000 museums in 47 countries,” Mr Chen said.

Countries that are signatories to a 1970 Unesco convention can request items taken from them only after that date, but Mr Chen said that China was not trying to reclaim the artefacts.

He said: “We have clarified that this is an attempt to document rather than to seek the return of those relics. We do hope some previously unknown relics might surface and some might be returned to our country during our investigation.”

In the British Museum, the China hall is full of porcelain that almost certainly came from the collections of emperors who lived in Yuan Ming Yuan.

Also in the collection is a series of paintings known as The Admonitions of the Instructress to the Court Ladies, a line drawing on silk believed to be the oldest of its kind in the world. The 8th-century copy of a parody by the artist Gu Kaizhi (about 345-406) was known to have been in the collection of the Qianlong Emperor (1736-96) and is believed to have been looted in 1900.

Under the command of Lord Elgin — the son of the man who acquired the Elgin Marbles — British and French troops looted the garden, also known as the Garden of Perfect Brightness. Lord Elgin wanted to punish the Emperor for the kidnap, torture and murder of 18 members of a 39-man diplomatic mission — including The Times correspondent Thomas Bowlby.

Two treasures that China wants to recover are in France. The bronze heads of a rabbit and a rat from a fountain featuring the 12 Chinese zodiac animals were auctioned as part of the estate of Yves Saint Laurent in February. A Chinese collector bid for them but refused to pay. Five others are back in China. The rest are missing.

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