Visitors to the World Athletics Championships are finding their mobile phones infected with a variant of the Cabir virus, which passes from phone to phone via a Bluetooth connection.
The Bluetooth phones have a range of up to ten meters but luckily the virus is an old variant which can only infect one phone at a time instead of the newer version which could have cause hundreds of infections in a very short period of time.
"At most we are speaking about dozens of infections, but during a short period and in one spot this is a huge number," security official at telecoms firm TeliaSonera Jarmo Koski told Reuters.
The recipient needs to accept the virus before it infects the handset. Once installed the virus runs the phone's batteries down while trying to infect another device.
Mikko Hyppönen, director of antivirus research at F-Secure said similar trends have occurred at other events.
"This happens easily when you gather tens of thousands of people from all over to world to a very small area. In fact, to some extent the same thing was happening during the Live8 concerts earlier this summer," he said.
Hyppönen added that staff from the company were now helping visitor to disinfect their phones.
As reported by SC Magazine earlier in the year, consultancy firm Deloitte predicted mobile phones would be under increasing attacks from viruses.