Madrid (CNN) -- A gang that used "ransomware" to infect and paralyze millions of computers in 30 nations has been broken up, the European police agency said Wednesday.
The gang, pretending to be police, told the computer owners that they had been caught in illegal online activity and had to pay a fine to regain use of their virus-locked computers, Europol announced in Madrid.
"What we saw in this operation was a new type of cybercrime problem, called ransomware, which involves in particular the cybercriminals hijacking the name and logo of a national police," said Rob Wainwright, director of Europol.
Wainwright, a British national, said even his own name and that of Europol was hijacked, as the suspects demanded, "a fine from citizens operating on the Internet. A fine for a fabricated offense, perhaps connected with suspected exchange of child sex abuse images or other such activity."
The gang demanded fines of €100 (about $134), Europol said.
The suspected ringleader of the gang, a Russian man, was arrested in the United Arab Emirates, while 10 suspected aides, including Russians, Ukrainians and Georgians, were arrested on Spain's Costa del Sol, on the Mediterranean coast, said Francisco Martinez, Spain's secretary of state for security.
At least 3% of the victims paid the fine, netting the gang an estimated millions of dollars, Wainwright said.
In Spain alone, investigators believe more than a million dollars in "fines" were paid by computer users, Martinez said.
Investigators had been on the trail of the suspects for about two years. When initially detected, the gang was operating only in six nations and had affected just 20,000 users, authorities said. Since then the scheme had expanded to 30 nations, mostly in Europe.
They managed to stay a step ahead of authorities by constantly changing mutations of the virus and their methods, authorities said. The Russian accused of being the leader of the gang is 27 years old, they said.
"We have identified one of the most dangerous criminal organizations working in this area ... and (are) closing down, therefore, a very important criminal market in this area," Wainwright said.
In Spain, more than 700,000 queries were sent to the government by users seeking advice on how to unblock their computers, Martinez said.