Police have apologised for making a fake suicide bomber shout "Allahu Akbar" before simulating blowing himself up during a counterterrorism exercise in Manchester. The simulated Islamic State (Isis/Daesh) terror attack saw a man dressed in black walk into the Trafford shopping centre and detonate prop explosives.

Hundreds of volunteers taking part in the exercise on Monday (9 May) then dropped to the floor screaming as gunfire erupted around them. Some wore "blood" make-up to simulate injuries while armed police taking part stormed the centre to take out the "terrorists".

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But the decision to have the suicide bomber in the exercise repeatedly shout the phrase "Allahu Akbar" – translated from Arabic as "God is great" – before detonating his explosives, led to criticism that the use of this stereotype would fuel anti-Muslim sentiment.

Dr Erinma Bell, a peace activist who was made an MBE due to her anti-gun violence work, said: "We need to move away from stereotypes if we want to achieve real learning. A terrorist can be any one."

The Community Safety Forum, which seeks to combat Islamophobia, also tweeted: "This sort of thing panders to stereotypes and further divides us. It will increase anti-Muslim hate crime."

The criticism has led Greater Manchester Police's Assistant Chief Constable Garry Shewan to apologise, calling it "unacceptable".

He said in a statement: "The scenario for this exercise is based on a suicide attack by an extremist Daesh (Isis)-style organisation and the scenario writers have centred the circumstances around previous similar attacks of this nature, mirroring details of past events to make the situation as real life as possible for all those involved.

"However, on reflection, we acknowledge that it was unacceptable to use this religious phrase immediately before the mock suicide bombing, which so vocally linked this exercise with Islam. We recognise and apologise for the offence that this has caused."

Some took to Twitter to question whether an apology was necessary. One user wrote: "Why apologise? This is a common element of #Islamist #terror attacks, so realistic I'd say."

Another added: "No need for an apology, or pandering to the easily offended. Just keep up the good work protecting Greater Manchester."

Monday's training, codenamed Exercise Winchester Accord, was one of the biggest counterterrorism exercises to be staged in the UK. Planned since December, around 800 volunteers took part with some playing dead or wounded. The exercise followed similar simulations which took place in London, Glasgow and Essex in recent months.