Police examine graves of Russian ex-spy's family in nerve agent investigation

• Video report by ITV News Wales & West of England Correspondent Rupert Evelyn

Police have widened their investigation over the nerve agent attack on Russian ex-spy Sergei Skripal and his daughter Yulia to the cemetry where their close family are buried.

Police were seen moving a tent over the grave of Mr Skripal's son, Alexander, who died last year at age 44.

There was also activity near the grave of Mr Skripal's wife, Ludmila, who died aged 59 in 2012.

It comes as military units arrived in Salisbury to help police investigating the nerve agent attack, which is being treated as attempted murder.

Home Secretary Amber Rudd, who visited the city today, is to chair a meeting of the Government's emergency Cobra committee on Saturday to get the latest updates on the case.

Fire officers in hazmat suits were seen pinning down a tent in the cemetery as firefighters, police officers and ambulance crews in regular uniforms stood nearby.

Other officers in white suits and gas masks were seen packing items from the cemetery into a yellow barrel.

It comes amid reports that the untimely deaths of Mr Skrippal's wife and son are now being investigated as part of the operation led by counter-terror police.

In the town centre, more than a dozen vehicles including Army lorries, unmarked white vans, police motorbikes and ambulances drove up to the A&E department at Salisbury District Hospital.

They are among scores of armed forces personnel including chemical warfare instructors and decontamination experts who will help investigate and clear a number of scenes around Salisbury linked to the attack.

Ms Rudd today made a personal visit to the city to meet victims and speak to officials.

She visited the hospital where three victims are being treated, and spent time with a police officer who was also poisoned after rushing to help Mr Skripal and his daughter.

Ms Rudd is known to have met Police Sargent Nick Bailey, who remains seriously ill in intensive care but is conscious and talking.

Former double agent Mr Skripal, 66, and his 33-year-old daughter are also being treated at the hospital and are in a "very serious" condition.

As many as 21 people, among them a number of police officers, are also feared to have been affected by the nerve agent and were offered treatment, according to Wiltshire police.

The arrival of military teams is intended to help carry out the specialised - and hazardous - process of investigating the attack and carrying out decontamination.

A total of 180 personnel from the Royal Marines, the RAF and chemical teams were deployed to Salisbury today.

They include chemical warfare instructors from the Defence CBRN Centre and a deployment from the 29 Explosive Ordnance Disposal and Search Group.

A number of Royal Marines from 40 Commando will be helping with the removal operation of items linked to the attack. They have recently trained for dealing with the after math of a chemical, biological or nuclear attack.

The military team also includes the Falcon Squadron, from Royal Tank Regiment, who will assist by setting up decontamination areas. An MoD source said these may resemble the tents seen during the Ebola outbreak in west Africa.

It is understood that the troops arriving at Salisbury District Hospital were working to remove a police car, which has been parked outside the A&E unit, behind a police cordon.

One bystander at the scene said: "it's mad" as they watched the vehicles roll in.

Much of Salisbury town centre also remains cordoned off over contamination fears.

Scotland Yard said the military presence was due to their specialist expertise and was not a cause for concern.

"The public should not be alarmed [that military units have been deployed] and the public health advice remains the same," a police statement said.

Police are continuing to investigate the attack on Mr Skripal and his daughter, which is being treated as attempted murder.

The case is being likened to the murder of ex-Russian spy Alexander Litvinenko, who died in the UK 12 years ago after being poisoned with the radioactive element polonium 210.

A public inquiry concluded in 2016 that Mr Litvinenko's killing had "probably" been carried out with the approval of Russian President Vladimir Putin.

With the Skripal investigation ongoing, officials have refrained from pointing the finger at Moscow.

On Thursday, Prime Minister Theresa May told ITV News that, should evidence prove the attack on Mr Skripal was state-sponsored, Britain would do "what is appropriate".

However, she stressed the police must be given time to carryout their investigations to decide who carried out the attack.

Nonetheless, the Russian embassy tweeted sulkily on Friday: "Investigation of Sergei Skripal case follows the Litvinenko script: most info to be classified, Russia to get no access to investigation files and no opportunity to assess its credibility."