An ancient Assyrian artefact stolen from one of the world's most significant archaeological sites has been returned to Iraq after 22 years of storage by police in London.

The British Museum played a pivotal role in returning the 9th-century BC carved panel.

Depicting a winged genie, the remarkable stone bas-relief once adorned the magnificent Northwest Palace at Nimrud, the Assyrian Empire's ancient capital, considered a cradle of world civilisation.

The site, on the Tigris river in modern-day Iraq, was repeatedly bulldozed and looted in 2014 by Islamic State terrorists, who denounced pre-Islamic art and architecture as idolatrous.

The panel was excavated at Nimrud in the early 1970s and disappeared in the chaos of the 1990s, after the end of the Gulf War sparked Saddam Hussein's invasion of Kuwait.

Ironically, its theft ensured its survival. Other reliefs that remained at the site were destroyed.

Dr St John Simpson, a senior Middle East curator and archaeologist at the British Museum, said: "It's the largest antiquity believed to have been repatriated to Iraq in the past 20 years, and very important as it has a perfect provenance.

"As a sculpture excavated by an Iraqi archaeologist at a capital of Assyria that was badly destroyed by Islamic State, it has added symbolic value."

The relief panel is substantial. Weighing around 52 stone, it is 5ft wide and 4ft long. Excavations in 19th century

The first major excavations at Nimrud took place in the mid-19th century, headed by Austen Henry Layard, an English politician and historian.

Various finds were brought to the British Museum, where they remain on display. Other institutions worldwide also hold items from Nimrud.

Details about the individual who acquired the genie relief in London have not been disclosed.

It was first identified in autumn 2002 and seized by the Metropolitan Police which has held on to it ever since. The reason for the delay in returning it to Iraq is unclear.

With British Museum staff as expert witnesses for the Iraqi government, the relief was handed to the Iraqi Embassy in London last week. The event was attended by the Met Police Art & Antiquity Unit.

Speaking at the event, Mohammed Jafar Al-Sadr, Iraq's ambassador to the UK, said the panel's "immense historical significance" had only increased following the destruction of the Nimrud palace site.

He also urged other individuals in possession of Iraqi artefacts to return them to their homeland.