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.

Those charges were dropped on Thursday, leading Queensland police to issue an arrest warrant "in relation to a number of alleged fraud offences".

Foster was on bail but didn't show in Downing Centre Local Court, with his lawyer telling the court he wasn't sure where Foster had gone after going to the lawyer's office in the morning.

"Queensland Police and NSW Police are currently making enquiries into his whereabouts," a Queensland Police spokesperson told AAP in a statement.

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.

Among his conditions, he was ordered not to leave his Dover Heights home except for a medical emergency, police reporting or to see his legal advisers.

He also had to surrender his passport, wear an electronic tracking anklet and was banned from using a mobile phone.

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Court papers for the since-withdrawn charges state the alleged fraud was valued at about $US1.141 million ($A1.73m) in January 2020, when the last transaction was said to have occurred.

The value of 120 Bitcoin was sitting around $A6.3 million on Thursday.

Australian Associated Press