The British government said Friday it will launch one of a largest ever simulated poison gas attack to test the emergency services' response to terrorism.

More than 2,000 policemen, firefighters and ambulance personnelwill take part in the drilling which will last from 0700 GMT until1500 GMT on Sunday in central England.

The location of the mock attack is being kept secret because itis feared that response times will be affected, if people know where to go beforehand, according to a BBC report.

Helen Braithwaite, the deputy director of the regional resilience team which has been planning the drilling since January,told the BBC that it will probably be the largest civilian chemical, biological, radiological and nuclear exercise of its kind in Britain.

"The exercise is not in response to any specific threat," she added.

"It's part of an ongoing program throughout the West Midlands --and the UK as a whole -- to ensure coordination of resources and communication between the different organizations involved," she said.

During the exercise, around 400 volunteers from the Army and Red Cross will be "contaminated" at a major public venue and then undergo a decontamination procedure, which involves having their clothes cut off and entering a special disinfecting shower, with the more seriously injured taken to hospital.

The exercise follows a simulated chemical attack on the London Underground in September last year when hundreds of people were evacuated from Bank station in London City.

Since then there have been similar exercises at several places around the country, including Newcastle-upon-Tyne in northeastern England and Abingdon, Oxfordshire, southern England.