Participants in US government-run cyberwar games tried to cheat - by hacking into the games. The shenanigans prompted organisers to send an urgent email telling the players to back off.

The Cyber Storm games took place over five days in February 2006 and involved the mock execution of attacks by anti-globalisation hackers against transportation, energy utility and corporate targets in the US and elsewhere. The arsenal of the "bad guys"included simulated computer attacks, physical attacks and psychological operations.

"Any time you get a group of (information technology) experts together, there's always a desire, 'Let's show them what we can do'," George Foresman, a former senior Homeland Security official told the Associated Press. "Whether its intent was embarrassment or a prank, we had to temper the enthusiasm of the players."

AP obtained censored records of the exercise under America's Freedom of Information Act. The government applied heavy use of black felt tips on most of the 328 pages it turned over, marked "For Official Use Only." Hundreds more documents remain under review.

But the released documents reveal an intriguing list of possible attacks including a scenarios that bloggers will spark protests and disruption by revealing the classified location of rail cars with hazardous materials. Another scenario examined what would happen if hundreds of people on the "No Fly" lists suddenly showed up at airport ticket counters.

The scenarios supply an insight into what keep disaster response planners awake at night. Mooted calamities included: the failure of railway switches and the compromise of water utilities in California, computer failures at border checkpoints and problems with satellite navigation systems. The black hats mounting the attack were imagined to be a loose coalition of hackers and other ne'er do wells, unwittingly aided and abetted by members of the media.

Homeland Security Secretary Michael Chertoff said the exercises were needed to build preparations against possible attack. "They point out where your expectations of your capabilities may be overstated," Certoff told AP. "It's a good way of testing that you're going to do the job the way you think you were. It's the difference between doing drills and doing a scrimmage," he added.

Results from the Cyber Storm war games, which cost $3m to stage and is described as the largest ever, have already been analysed, if not publicly released. But did mock society crumble under the mock assaults. Reviews are said to be mixed, with the sheer volume of assaults exacerbating confusion on who to report attacks to a particular problem. In other cases, responses were well executed, according to reports.

Government officials from the UK, Canada, Australia and New Zealand and executives from IT and transport firms joined US counterparts to conduct the exercise.

To stop the games spilling onto the public internet the attacks were simulated on isolated computers, run from the basement offices of the Secret Service's Washington headquarters.

The Department of Homeland Security is holding a sequel to the games, dubbed Cyber Storm 2, in March, which will involve simulated electronic attacks against chemical plants and communication networks, AP reports. ®