A Canadian court on April 11 declined to release on bail a man accused of working with Russian intelligence agents in the largest-ever e-mail hacking scheme, calling him "a valuable operative for the FSB."
The court said the man, Karim Baratov, 22, a Canadian citizen who was born in Kazakhstan, posed a flight risk.
U.S. authorities say Russian agents paid Baratov to break into at least 80 e-mail accounts. They are seeking his extradition to face charges of computer fraud, wire fraud, and identify theft.
Baratov denies the charges.
Media reports said Canada will be ready to proceed with an extradition hearing by June 12.
The United States last month charged Baratov, two Russian intelligence agents, and another alleged hacker over the 2014 theft of 500 million Yahoo accounts, the first time the U.S. government had criminally charged Russian spies for cyberoffenses.
The other alleged hacker is Aleksei Belan, one of the FBI's most-wanted cybercriminals who was arrested in Europe in June 2013 but escaped to Russia before he could be extradited to the United States.