Israel's internal intelligence service urged the public Monday to exercise caution when using Facebook, saying Arabs are trying to recruit spies on the popular social networking site.
The Shin Bet security agency warned Israelis against answering unsolicited messages or sharing telephone numbers and other sensitive information over the Internet. It said there have been numerous incidents recently in which violent groups tried to recruit Israelis through Facebook and other networking sites.
The agency said in one instance an Israeli Facebook user was contacted by a man who introduced himself as a Lebanese agent and offered money for information about Israel.
The Shin Bet said Israelis should be wary of seemingly innocent meetings or dates proposed online by people they don't know. These messages might be posted by militants with intention to kidnap or kill, it said.
"Terror organizations are using these sites to tempt Israelis to meet up in person in order to either abduct them, kill them or recruit them as spies," the Shin Bet said.
An Israeli teenager was killed eight years ago when he was lured to the West Bank by a young woman he met on the Internet.
In recent years, militants have turned to the Internet to battle Israel. Hamas militants in the Gaza Strip have long been using Google Earth for better precision when firing rockets at southern Israeli cities.
Facebook is open to any person, group or business that wants to sign up for an account. It does prohibit content that is hateful or threatening, and users are barred from doing "anything unlawful, misleading, malicious, or discriminatory." But, like elsewhere on the Internet, Facebook does not hand-screen all the content on the site before it is posted.
Facebook officials did not immediately respond to a request for comment.
Two Israeli Arabs were arrested on charges they gave strategic information to the al-Qaida terror network over the Internet last year.
Last year, an Israeli reservist was sentenced to five years in prison for sending e-mails offering to sell secret information to Iran and Hamas.
Israel frequently issues travel warnings to its citizens citing intelligence reports of militant plots to attack and kidnap Israelis.