The alleged mastermind of the major cyber threat facing all computer users goes by the online moniker "lucky12345".

And Evgeniy Mikhailovich Bogachev will need all the luck he can find to evade justice - because he currently sits at the top of the FBI cyber-crime 'most wanted' list.

The Russian man (30) is said to be the leader of the gang accused of stealing more than US$100 million (€73.4m) by installing viruses on hundreds of thousands of computers around the world.

US authorities say the group - whose members come from Russia, Ukraine and Britain - infected computers with software that captured passwords and account numbers, allowing them to steal from their victims.

The racketeering enterprise has been installing the malicious software, such as GOZeuS and CryptoLocker, on computers since 2009.

The botnet used to carry out the attacks has been temporarily disrupted, and computer users have been warned they have just two weeks to improve their online security.

The clock is ticking for computer users around the world, but also for Bogachev, who is thought to be in a location somewhere in Russia or around the Black Sea.

He is a keen boater and is known to sail around the Black Sea, bordered by countries including Bulgaria, Turkey and Georgia. He was last known to reside in Anapa, Russia, and also owns property elsewhere in the country in Krasnodar.

Bogachev's 'Wanted' poster from the FBI

He is described as 5-foot-9 inches tall and weighs around 81 kilogrammes. He has brown hair but in most photographs he has a shaved head.

Bogachev is "a true 21st century criminal, who committed cyber crimes across the globe with a stroke of a key and the click of a mouse" said James Cole, US deputy attorney general.

The FBI describes Bogachev as the "administrator" of the racket, but says others are involved in the scheme by distributing spam and phishing e-mails.

It added "Victims who visited these web sites were infected with the malware, which Bogachev and others utilised to steal money from the victims' bank accounts".

The FBI has been investigating the fraud since the summer of 2009. Bogachev also uses the online handles "slavik" and "Pollingsoon".

Criminal and civil allegations were filed in Pittsburgh against Bogachev because some of the victims were from western Pennsylvania.

The charges included conspiracy, wire, bank and computer fraud, and money laundering.

The victims of the different schemes include an American-Indian tribe in Washington state; an insurance company and a company that runs assisted-living centres in Pennsylvania; a local police department in Massachusetts; a pest control company in North Carolina; and a restaurant operator in Florida.