Eugeni "Zhenya" Tsvetnenko, 39, was charged by New York authorities in mid-2016 with offences including wire fraud, arrested at his Perth home in December last year and remains at Hakea Prison.

The father-of-two has repeatedly failed in his bid to secure bail, with the High Court recently refusing to hear his case.

He argues he's not a flight risk, given he learnt of the charges more than two years prior to his arrest, and offered to surrender his passports.

His lawyers have also argued he has special circumstances, including depression, shared care of young children and a painful spinal condition that requires hydrotherapy.

A statement issued by Tsvetnenko's spokeswoman on Monday cited Mr Robertson as saying the refusal to grant bail was "entirely unnecessary and cruel".

"Our courts cause real cruelty to people they lock up for years and deprive of the presumption of innocence, simply because it is a foreign country which wants to put them on trial," Mr Robertson said.

"If there is no real prospect that an Australian will flee they should be entitled to stay at liberty to fight what may well be a fabricated case against them.

"Otherwise, they will spend years in jail before they get the chance of a trial."

Tsvetnenko is due to face a two-day extradition hearing starting March 5.

It is alleged he and co-offenders charged mobile phone customers $US9.99 per month for unsolicited, recurring text messages about horoscopes, celebrity gossip and trivia between 2011 and 2013.

Illegal profits totalling more than $US150 million were allegedly used to fund lavish lifestyles.

Those nabbed in the investigation include Darcy Wedd and Fraser Thompson, who were sentenced to 10 years and five years behind bars, respectively.

Australian Associated Press