Anti-terrorist exercise taking place in Surrey Street and the site of the former Aldwych underground station. Image: Met Police

A major anti-terrorist exercise taking place in central London over the next two days is to prepare the emergency services for a Mumbai or Charlie Hebdo style attack.

The Metropolitan Police Commissioner, Sir Bernard Hogan-Howe said: ‘ Should the worst happen we are ready. And we will be.’

Operation Strong Tower has been planned for around six months.

Specialist Ambulance Teams taking part in today's #999Exercise delivering pt care in the most difficult environment http://t.co/pnb9jrBMbJ

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Pete Brown (@Ambo_Pete) June 30, 2015

Sir Bernard said ‘As people will be aware, the threat level for terrorism has been raised over the last year and it is vital that we train and we learn.’

He added:

Today’s exercise will test our people in how to respond to a terrorist threat and we will learn from the mistakes that we are bound to make today. It’s best we make them today in an environment were we don’t have terrorists, than make those mistakes when we do.

The Commissioner continued:

Over the last year the rate of arrests has increased. We are arresting about one person a day for terrorist offences. It is clear during that time that we’ve disrupted some very serious plots and some of those cases are going to the courts. The reason we have exercises like today is because, obviously, we are concerned there are people planning terrorist events.

We intend first of all to stop them from getting to attack. But should we not stop the terrorists in their planning, it’s essential we disrupt them in any of the attacks that may take place.

***THIS IS A TRAINING EXERCISE*** Simulated gun attack in central London to train emergency services http://t.co/Ej7uSwTWLs

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Mark White (@skymarkwhite) June 30, 2015

The #999Exercise will test communication structures between the emergency services including @TFL @GovUK & #LDN_gov ow.ly/OYhPo

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Metropolitan Police (@metpoliceuk) June 30, 2015

Don’t worry if you see lots of emergency services vehicles near #Aldwych, we are training today #999exercise http://t.co/BnHnykbmXU

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London Fire Brigade (@LondonFire) June 30, 2015

We're involved in an exercise with @metpoliceuk to test our response to a major incident #999Exercise

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London Ambulance (@Ldn_Ambulance) June 30, 2015

Surrey Street near #Temple will be closed to all traffic today #999Exercise ow.ly/OYlwp

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Metropolitan Police (@metpoliceuk) June 30, 2015

David Brown is Director of Operations @LondonFire. He told me this kind of #999Exercise is essential. @BBCLondon949 http://t.co/pSm17ziQOz

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Anna O'Neill (@Annareporting) June 30, 2015

Today's #999Exercise will take place at the disused #Aldwych tube station in Surrey Street ow.ly/OYmG1

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Metropolitan Police (@metpoliceuk) June 30, 2015

If you are out & about near the #Strand today - there is a #999Exercise happening close by - not a real incident ow.ly/OYrTT

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Metropolitan Police (@metpoliceuk) June 30, 2015

Footage from the scene down at #Aldwych tube station #999Exercise - not a real incident amp.twimg.com/v/d9d5c97c-e52…

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Metropolitan Police (@metpoliceuk) June 30, 2015

Our advanced trauma teams are involved in major incident exercise with @metpoliceuk & @Ldn_Ambulance & @LondonFire today #999Exercise

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London'sAirAmbulance (@LDNairamb) June 30, 2015

We regularly practise responding to emergencies with @metpoliceuk @Ldn_Ambulance @BTP @TFL london-fire.gov.uk/news/LatestNew… http://t.co/iTlimvhHL4

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London Fire Brigade (@LondonFire) June 30, 2015