An arrest warrant for Foster has been issued in Queensland after prosecutors in Sydney dropped more than a dozen charges over an alleged multi-million-dollar Bitcoin scam.

The 58-year-old was facing 15 fraud charges after allegedly posing as a man called Bill Dawson and extricating 120 Bitcoin from a Hong Kong man in 2019 and 2020.

Foster's lawyer Chris Hannay said the fresh Queensland charges related to those dropped south of the border, and he believes there are 'significant issues' with the brief.

"There's been an internal investigation in Sydney over it, within the police department," he said on Wednesday.

NSW Police said it would be inappropriate to comment "as the matter is currently the subject of an internal investigation".

While Foster was a 'charismatic crook' and a 'charismatic good bloke', he's 'not the villain in this', Mr Hannay said.

A Sydney court in February was told police were yet to directly take a statement from the complainant.

"The whole prosecution relies upon investigations not conducted by the police but a private investigator and his own reasons," lawyer Angelo Bilias said at the time.

Court papers for the since-withdrawn charges state the alleged fraud was valued at about $US1.141 million ($A1.73m) in January 2020, when the last transaction was said to have occurred.

Foster was arrested on a beach in far north Queensland in August 2020 before being extradited to Sydney.

He spent seven months in custody until a magistrate granted him strict bail on March 26.

Australian Associated Press