The United States will return to Iraq some 17,000 archaeological treasures dating back 4,000 years and looted in recent decades, an "unprecedented" restitution, the culture minister in Baghdad said Wednesday.

Iraqi Prime Minister Mustafa al-Kadhemi was set to take back the artifacts from ancient Mesopotamia on his aircraft, when he returns Thursday from Washington where he met US President Joe Biden.

"This is the largest return of antiquities to Iraq," said Iraqi Culture Minister Hassan Nazim, hailing it as "the result of months of efforts by the Iraqi authorities in conjunction with their embassy in Washington".

Most of the ancient pieces document "the commercial exchanges during the Sumerian period", his ministry said in a statement.

Iraq's antiquities have been extensively looted during decades of war and insurgency, often by organised crime groups, since the 2003 US-led invasion that toppled Saddam Hussein.

"It is impossible to quantify the number of pieces that have been stolen from archaeological sites," Qahtan al-Obaid, director of antiquities and heritage at the Basra Museum, told AFP. 

Archaeological sites across the country have been severely damaged and neglected, and museums looted, with some 15,000 pieces stolen from Iraq's only national museum in Baghdad.

"I hope that in the near future we will be able to recover the rest of our goods, especially in Europe," said Nazim in his statement.  

Looted artifacts

Among the pieces to be returned to Iraq is a 3,500-year-old clay tablet with a sequence from the epic of Gilgamesh, which once sat in Washington's Museum of the Bible, the US Department of Justice said separately in Washington.

It was not immediately clear whether the "Gilgamesh Dream Tablet" would be among the 17,000 pieces to be returned this week.

The rare fragment, which recounts a dream sequence from the epic in Akkadian cuneiform script, is one of many ancient artifacts from the Middle East collected by David Green, the billionaire owner of the Hobby Lobby chain of arts and crafts stores.

It was seized by the US Justice Department in 2019, two years after Green opened the museum dedicated to ancient Christian history in downtown Washington.

The tablet was just one of thousands of Iraqi-origin artifacts, mostly 3,000- to 4,000-year-old cuneiform tablets and seals, that have been seized from Hobby Lobby and the Bible Museum for repatriation to Iraq.

The Justice Department said they were plundered in Iraq, and traded illegally by dealers in Israel and the United Arab Emirates.

According to the Justice Department, Hobby Lobby bought the six-by-five-inch (15.2 by 12.7 centimetre) tablet from a prominent auction house in 2014 for $1.67 million.

It had originally been brought illegally to the United States in 2003 by a dealer, who purchased it in London from a well-known Jordanian trader of ancient Middle Eastern antiquities.

It was then traded several times with false letters of provenance to assure buyers that it was legally obtained, rather than a product of the underground antiquities trade.

In 2014, Hobby Lobby arranged to buy the tablet in New York, but carried out the transaction in Oklahoma to avoid sales taxes, according to the Justice Department.

The company then donated it to the collection of the Museum of the Bible.

Since the tablet was seized in 2019, the Justice Department has pursued formal ownership through forfeiture laws to be able to return it to the rightful owners.

"This forfeiture represents an important milestone on the path to returning this rare and ancient masterpiece of world literature to its country of origin," said acting US attorney Jacquelyn Kasulis of the eastern district of New York.

"This office is committed to combating the black market sale of cultural property and the smuggling of looted artifacts," she said in a statement.