FILE PHOTO: A tattered flag bearing the Yahoo company logo flies above a building in New York, U.S., October 31, 2016. REUTERS/Lucas Jackson/File Photo - RTS16VVU

TORONTO (Reuters) - In his first U.S. court appearance on Wednesday, Canadian Karim Baratov pleaded not guilty to charges that he helped Russian agents in a high-profile cyber attack on Yahoo email accounts, his lawyer said.

Baratov, a 22-year old Canadian citizen born in Kazakhstan, was arrested in Canada in March at the request of U.S. prosecutors. They charge he was paid to break into at least 80 email accounts by Russian intelligence agents who masterminded the 2014 theft of data from some 500 million Yahoo Inc YHOO.O user accounts.

Baratov entered his plea during a brief appearance at the U.S. Federal Court in the Northern District of California, lawyer Andrew Mancilla said. His next hearing is scheduled for Tuesday.

Mancilla declined to comment on prospects for a plea bargain for Baratov, who presented himself on social media accounts as a wealthy young man who loved expensive cars. He waived his right to fight the U.S. request for him to be extradited from Canada.

Baratov is the only person arrested to date among four men indicted in the case. The others include Alexsey Belan, who is among the FBI’s most-wanted cyber criminals, along with two officers in Russia’s Federal Security Services - Dmitry Dokuchaev and his superior, Igor Sushchin.