An American sex offender wanted in Australia for child pornography offences has been arrested in Missouri on similar counts, US authorities say.
Timothy R Powers, 57, was jailed in Australia more than a decade ago for child pornography offences and eight months ago, with NSW police issuing warrants for his arrest on new charges, he fled to the US.
"He has outstanding charges in Australia for possession of child pornography," Lieutenant David Tiefenbrunn, of the St Charles County Sheriff's Department in Missouri, told AAP on Friday.
"That was one of the reasons he fled Australia - to avoid prosecution on that case.
"He's already been convicted in the past in Australia and has served time for possession of child pornography."
St Charles sheriffs received an anonymous tip earlier this week that Powers was downloading child pornography at his home in Weldon Springs, near St Louis.
An investigation was launched, his computers were seized and he was charged with possession of child pornography and failure to register as a sex offender.
Powers, a US citizen, is being held in the St Charles County Department of Corrections on $US50,000 ($A55,600) bond.