GENEVA (Reuters) -- A UN agency charged with helping member nations secure their national infrastructures plans to issue a stern warning about the risk of the Flame virus that was recently discovered in Iran and other parts of the Middle East.

"This is the most serious warning we have ever put out," said Marco Obiso, cyber security coordinator for the UN's International Telecommunications Union.

The confidential warning will tell member nations that the Flame virus is a dangerous espionage tool that could potentially be used to attack critical infrastructure, he said in an interview.