The Android operating system accounted for 79 percent of all malware infections on smartphones, and the threat is multiplying, a security firm said Thursday.

Finland-based F-Secure said in a report that the free Google operating system, which has been gaining smartphone market share globally, has become the dominant platform targeted by hackers.

"Every quarter, malware authors bring forth new threat families and variants to lure more victims and to update on the existing ones," the F-Secure quarterly report said.

"In the fourth quarter alone, 96 new families and variants of Android threats were discovered, which almost doubles the number recorded in the previous quarter."

The only other platform with any significant share of malware was Symbian, the system dropped by Nokia, which F-Secure said accounted for 19 percent.

Other major platforms including Apple's iOS, BlackBerry and Windows Phone each had less than one percent of mobile phone infections.

"Blackberry, iOS, Windows Mobile, they may see some threats popping up once in a while. But most likely, the threats are intended for multiple platforms," the report noted.

F-Secure said some of the threats included "shady SMS-sending practices" that can sign up victims to an SMS-based subscription service.

Other malware includes banking trojans, designed to steal passwords for online accounts and transfer money from the victims' accounts.

One of these, called Eurograbber, came as a PC virus but tricked users into installing a version on their mobile device, and has been linked to the theft of $47 million from European customers, F-Secure said.

The report said Android malware has outpaced its share of the overall market. While its market share rose to 68.8 percent in 2012, its malware share rose to 79 percent from 66.7 percent the previous year.