Alfred Taubman: "Surprised and disappointed"

If found guilty of the conspiracy charges the pair face a maximum sentence of three years in prison, plus a $350,000 fine.

"This case will show that these individuals mastered the art of price fixing," said James Griffin, deputy attorney general in charge of the criminal antitrust enforcement programme.

But Mr Taubman, chairman of Sotheby's for 17 years, on Wednesday protested his innocence, saying he was "surprised and disappointed by the charges".

"While any trial is difficult, I look forward to the opportunity to clear my name in court," he said.

Long-running probe

Wednesday's indictment is the latest twist in a four-year probe by US justice chiefs into the $4bn art auction industry.

Sotheby's itself, and former chief executive Diana Brooks, in October pleaded guilty to price-fixing charges.

A New York judge in February agreed a $45m settlement by Sotheby's over the charges.

Ms Brooks has not been sentenced.

Christie's received conditional immunity from prosecution for co-operating with the Department of Justice probe.

Class action

Last month, both auction houses received court approval for a $512m settlement to a civil 'class action' suit brought on behalf of 130,000 former customers.

Mr Taubman, a US citizen who still owns a controlling share in Sotheby's, and Ms Brooks stood down from the auction house in February 2000.

Mr Tennant, a UK citizen, worked at Christie's from 1993-96.