That piece just happened to be a buttock.

Derbyshire police told The Guardian that the man was detained on suspicion of breaching the 2003 Iraq Sanctions Order, which governs the importation of "Iraqi cultural property" – including items of archaeological, historical or religious importance.

The bronze buttock cheek was saved from being melted down for scrap metal by the 52-year-old former SAS soldier Ely after he witnessed the statue being toppled by US marines in Baghdad in 2003.

The report said it is understood that the arrested man is connected to Derby-based war art relic company Trebletap, which was allegedly attempting to find a buyer for the souvenir on behalf of Ely.

As well as expressing shock at the arrest, Ely described the Iraqi authorities' claim to be rightful owners of the bronze as "like the Elgin Marbles with attitude".

Describing the furore surrounding the buttock as farcical, Ely questioned how a piece of metal from a statue put up by a dictator could be classified as national cultural property.

"How can it be classed as cultural property when it was put up by the biggest tyrant since Attila the Hun," the former soldier asked.

Ely believes that Iraqi officials decided to demand the return of the war relic after seeing media coverage of its value. "The piece has been independently valued at £250 000 and I think that's why the Iraqis want it," Ely said.

"American Marines gave it to me and at that time Baghdad was under American control," he added. "There wasn't even an Iraqi government and I have since turned it into a piece of war relic art.

"This is like having a chunk of the Berlin Wall – it's part of history but it's not cultural property."

Police have also interviewed Ely about the statue and requested that he sign a document warning him that if he sold or defaced the buttock he could face prosecution.

A 66-year-old man was arrested for trying to help Ely sell the buttock.