An international operation has dismantled a global computer hacker network, which used a sophisticated computer virus to steal millions of dollars from companies and consumers.

The US Justice Department said that Gameover Zeus, which first appeared in September 2011, stole bank information and other confidential details from victims.

The virus infected between 500,000 and a million computers in 12 countries, creating a network the hackers could "infiltrate, spy on, and even control, from anywhere they wished".

It encrypted the computers of its victims and demanded a ransom, often in excess of $700, in exchange for the password to unlock it.

Investigators say the cyber criminals amassed more than $27m in just the first two months.

FBI Executive Assistant Director Anderson said: "Gameover Zeus is the most sophisticated botnet the FBI and our allies have ever attempted to disrupt."

The FBI blamed Gameover Zeus for the theft of more than $100m (€73m), obtained by using the stolen bank data and then "emptying the victims' bank accounts and diverting the money to themselves".

The operation also targeted another computer virus, dubbed "Cryptolocker," which appeared in September 2013.

Russian Evgeniy Mikhailovich Bogachev, 30, an alleged administrator of the network, was charged in Pittsburgh, Pennsylvania.

He was charged with 14 counts, including conspiracy, computer hacking, bank fraud and money laundering in the Gameover Zeus and Cryptoblocker schemes.

Mr Bogachev was also charged in Omaha, Nebraska with "conspiracy to commit bank fraud" in relation to an earlier incarnation of Gameover Zeus.

"Evgeniy Bogachev and the members of his criminal network devised and implemented the kind of cyber crimes that you might not believe if you saw them in a science fiction movie," said Leslie Caldwell, deputy attorney general.

US investigators worked with counterparts in Australia, the Netherlands, Germany, France, Italy, Japan, Luxemburg, New Zealand, Canada, Ukraine, and Britain, as well as the European Cybercrime Centre, according to a statement.

They were also aided by private companies, including Dell, Microsoft, Afilias, Deloitte and Symantec.