The defendants targeted US banks and stole about $1.5m from hundreds and possibly thousands of account holders, the FBI said yesterday.

More than 50 individuals in California, Nevada, and North Carolina, and nearly 50 Egyptians were charged with crimes including computer fraud, conspiracy to commit bank fraud, money laundering, and aggravated identify theft.

FBI director Robert Mueller described the events as a "cyber arms race," where law enforcement and criminals competed to stay a step ahead of each other.

The two-year investigation was led by the FBI's Los Angeles office, and included the Secret Service, the Electronics Crimes Task Force in Los Angeles, state and local law enforcement, and our Egyptian counterparts. This was the first joint cyber investigation between Egypt and the US, he said.

Mueller said it was hard to tell what investigators were getting into at the start of a case. "Something that looks like an ordinary phishing scam may be an attempt by a terrorist group to raise funding for an operation," he said. Money appeared to be the driving motive in Operation Phish Phry.

Mueller said cybercriminals still outnumbered cybercops, even with strong cooperation between national and international law enforcement agencies.

The Anti-Phishing Working Group, a industry consortium, reported that 49,084 unique phishing web sites were set up in June, the second most recorded in a single month.

Mueller called on people to protect their home computers with firewalls, anti-virus software, and strong passwords. "We all have a responsibility to protect the infrastructure that protects the world," Mueller said.

This article first appeared in Computer Weekly.