A British history professor played a central role in an elaborate FBI sting to catch a Smithsonian curator selling military artifacts from the United States' national collection, it has been revealed.

John Hall, a graduate of Sussex and Oxford, teaches colonial, revolutionary and military history at Albion College, a small Michigan college of about 1,600 students.

Working undercover, he posed as an unsuspecting collector in meetings with the Smithsonian Institution employee while the FBI listened in. They recruited him after he alerted the agency to his suspicions that a thief was at work in the first world war aviation collection.

Last December Karl Schneide, a curator who oversaw the collection, was jailed for six months after pleading guilty to stealing 18 pieces of government property. He was ordered to pay $20,000 restitution.

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Dr Hall defended his role saying he was only a "co-operating witness. I was outraged, and what academic can't be?" he said. "Mr Schneide was not just stealing from the American people, breaking his position of trust, but stealing from the global community of scholars, from current and future researchers."

In 1994, looking for aviation items to buy, Dr Hall was offered two rare fabric pieces from first world war planes by a Pennsylvania dealer for $3,000. An expert he contacted had seen similar items in the Smithsonian's warehouse and mentioned Schneide's name.

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Dr Hall set out to win the curator's confidence. His home and office phones were wire-tapped. Armed with FBI cash, Dr Hall bought an aviator's jacket, a key piece of evidence. Mr Schneide also gave him a private tour of the National Air and Space Museum in Washington, part of the Smithsonian. "I felt rather as though I was shopping," Dr Hall said.