Two US men have been convicted for their part in an international spam operation which bombarded internet users with explicit adult content.

A Federal jury convicted James R. Schaffer, of Paradise Valley, Arizona, and Jeffrey A. Kilbride, of Venice, California, on multiple charges including conspiracy, money laundering, fraud and transportation of obscene materials.

Spam sent by Schaffer and Kilbride resulted in AOL receiving more than 600,000 user complaints between 30 January and 9 June 2004.

Assistant attorney general Alice Fisher said that the spam messages, which promoted pornographic websites, grossed the two men more than $2m.

"This dirty duo used a variety of tricks to try and hide their whereabouts from the US authorities," said Graham Cluley, senior technology consultant at Sophos.

"This included logging-in remotely to servers based in Amsterdam to make their spam messages appear to be of non-US origin, and using bank accounts in Mauritius and the Isle of Man.

"The spammers worked hard to protect themselves and disguise their identities, but did not lose any sleep over the hundreds of thousands of innocent families and children who were receiving their unwanted explicit emails."

Schaffer and Kilbride face up to five years in prison for each spam and obscenity offence. In addition, they face a fine of up to $500,000 and a maximum 20-year prison sentence for money laundering. Sentencing is scheduled for 24 September.

Other members of the gang, including work-at-home 'mum' Jennifer Clason and Kirk Rogers of Manhattan Beach, California, have already admitted their involvement in the international spam operation.