According to Australian Associated Press news agency counter-terrorism agents are investigating terror threat against an Australian through social networking website Facebook.

This is the first investigation of this kind. News reports say that a threat came from an alleged Hezbollah member to a Jewish woman.

After declining his friend request she received numerous death threats from the self-proclaimed terrorist.

The man, who described himself as Ibrahim Dirani, is a member of the Lebanon-based Facebook group.

After police launched the investigation against him this week, Dirani was banned from the site, according to various news reports.

Melbourne woman who is a member of an Israeli-based Facebook group told the police the alleged Hezbollah supporter promised to kill her and her family.

“The international nature of the website makes it very hard for agencies to… physically track down those involved,” a security source said.

“People on those websites often set up their pages under false details.”

Counter-terrorism expert Anthony Bergin warned Facebook users that terrorist networks might use the website for recruiting, and Canadian Defence Department issued several warnings back in February that al-Qaeda operatives were monitoring Facebook.