The US government has announced a $3m reward for information leading to the arrest of a man American authorities call one of the world's most prolific cyber hackers.

Evgeniy Bogachev was indicted in Pittsburgh last year on charges including bank fraud and conspiracy. His pictures have been plastered on "Wanted" signs distributed by the FBI.

Bogachev is charged in the United States with running a computer attack network called GameOver Zeus that allegedly stole more than $100m from online bank accounts.

He also faces federal bank fraud conspiracy charges in Omaha, Nebraska related to his alleged involvement in an earlier variant of Zeus malware known as "Jabber Zeus".

Bureau officials said they believed Bogachev was still in Russia. He could not immediately be reached for comment by the Reuters news agency.

Joseph Demarest, head of the FBI's cyber crime division, said the agency was aware of 60 different cyber threat groups linked to nation-states. He did not identify which countries were believed to be behind these groups.

Demarest said that Russia's internal security agency, the FSB, had recently expressed tentative interest in working with US authorities on investigating cyber crimes. He did not link the offer of cooperation to the Bogachev case.

Despite the reward, which the US Justice Department and State Department announced on Tuesday, arresting overseas hackers is difficult for US authorities, particularly in countries like Russia where there is no extradition treaty.

Source: Agencies