US computer security authorities warned on Friday that online scammers may seek to exploit the earthquake in Japan.
The US Computer Emergency Readiness Team (US-CERT) told computer users to be wary of "potential email scams, fake antivirus and phishing attacks regarding the Japan earthquake and the tsunami disasters."
"Email scams may contain links or attachments which may direct users to phishing or malware-laden websites," US-CERT said in a statement.
"Fake antivirus attacks may come in the form of pop-ups which flash security warnings and ask the user for credit card information," it said.
"Phishing emails and websites requesting donations for bogus charitable organizations commonly appear after these types of natural disasters," US-CERT added.
Phishing refers to attempts to steal user names, passwords and other personal information from unsuspecting victims, mostly through email or instant messages.
The massive, 8.9-magnitude quake left hundreds dead in Japan and unleashed a tsunami in the Pacific.