A huge emergency exercise will involve hundreds of people and see military helicopters circling the skies of Greater Manchester.

Exercise Triton II – the biggest live exercise ever held in the region – will test how emergency services and other local organisations respond to a major incident.

The exact details for the ‘disaster’ exercise have not been disclosed.

However, organisers say it will include a mock live response search and rescue operation in the Oldham and Rochdale areas on Thursday, July 14 and are warning people not to be alarmed.

Police , firefighters and paramedics will join forces with 33 ‘partner’ agencies including local councils, the military and search and rescue teams during the day.

The exact locations will not be publicised until the day of the exercise, but residents nearby are being warned about any unusual activity.

There will be infrequent air activity in Oldham and Rochdale from 10am to 10pm – including the use of military helicopters.

Paul Argyle, chair of Greater Manchester Resilience Forum, said: “Exercises like this are hugely important to ensure – as a region – we are prepared to deal with a real-life major event or disaster, should it occur.

“Police, firefighters and paramedics will work side-by-side with around 33 partner agencies including local councils, utility companies, the military and specialist search and rescue teams to respond to the disaster during that week.

“The scale of the scenario will give these organisations a vital opportunity to practise skills and functions that are rarely used but are necessary in the event of a major incident.

Greater Manchester Police helicopter

“I would like to assure residents across the region that it will be business as usual during this exercise.

“I would also like to express my thanks to all the volunteers who will be taking part. With them on board we will be able to ensure we provide the best support possible for our residents and communities should such incidents occur.”

Other local councils, health, transport and utility organisations will be put to the test during Thursday’s exercise.

Under the Civil Contingencies Act 2004, it is a requirement for local authorities and emergency services to plan for major incidents and Category 1 responders.

In May Greater Manchester Police staged one of Britain’s largest-ever counter terrorism training exercises, in the Trafford Centre.