London (CNN) Around 180 British troops have been deployed to the English city of Salisbury to aid in the investigation of a nerve agent attack on a former Russian double agent and his daughter.

Personnel from the Royal Air Force, British Army and Royal Navy were among those sent to Salisbury on Friday, a Ministry of Defence spokesman told CNN.

London's Metropolitan Police tweeted that the public should not be alarmed and the public health advice remained the same. It explained that the counterterrorism division had requested assistance from the military to "remove a number of vehicles and objects from the scene."

A split image showing former Russian spy Sergei Skripal and his daughter, Yulia Skripal.

Former Russian spy Sergei Skripal, 66, and his daughter Yulia, 33, were still hospitalized in "very serious condition" after being poisoned earlier this week, UK Home Secretary Amber Rudd said as she visited Salisbury on Friday.

The pair -- believed by authorities to have been deliberately targeted -- were found slumped on a bench near a shopping center on Sunday afternoon.

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