TORONTO -- Lawyers for a Canadian accused in a massive hack of Yahoo emails will be in an Ontario court Monday to fight a judge's decision to deny the man bail.

Karim Baratov is appealing an April ruling by Ontario Superior Court Justice Alan Whitten, who found the 22-year-old was too much of a flight risk to be released on bail.

The judge also said Baratov's parents would not make suitable supervisors because they had not questioned his growing wealth or his business activities while he was living with them.

Baratov was arrested in March under the Extradition Act after U.S. authorities indicted him and three others -- two of them allegedly officers of Russia's Federal Security Service -- for computer hacking, economic espionage and other crimes.

The breach at Yahoo affected at least a half billion user accounts, but Baratov is only accused of hacking 80 accounts.

In an application for a review of the bail decision, Baratov's lawyers argue Whitten "made a number of errors in principle."

They say the judge "made findings related to the applicant's conduct that are not supported by evidence and are in fact contrary to the evidence."

The defence had proposed that Baratov be released on house arrest in the care of his parents, who offered close to $1 million in money and assets as collateral.

Baratov, who lived in Hamilton, would also have been required to turn in his travel documents and abstain from owning or using any computer or electronic communication device.

But Whitten said Baratov would be particularly motivated to flee given that he could face as much as 20 years in prison if convicted in the U.S., and would be able to ply his alleged trade from anywhere in the world.

The judge also said the potential financial loss that could come about if Baratov were to violate his bail would mean nothing to someone with allegedly endless sources of income, and pointed to Baratov's social media photos -- particularly one in which he posed with a fan of $100 bills -- as a sign of the young man's "cavalier attitude towards money."

American authorities have alleged in court documents that Baratov, who was born in Kazakhstan, posed an "extremely high flight risk" in part due to his alleged ties to Russian intelligence agents and his financial resources.

A hearing later this month is expected to set the date for Baratov's extradition hearing.