LONDON • Britain was to hold a second meeting of its national emergencies committee yesterday in response to a nerve agent attack on a Russian former spy.

Home Secretary Amber Rudd was to chair the meeting of the committee, known as Cobra, to receive updates on the police case, the government said.

The British authorities investigating the poisoning of Mr Sergei Skripal and his daughter have visited the graves of Mr Skripal's wife and son in Salisbury, England.

Dressed in large hazardous-material suits, the investigators began collecting evidence at Mr Skripal's house in the town last Friday and erected a blue forensic tent around the grave of the son. Police said they had requested military assistance to "remove a number of vehicles and objects from the scene".

Mr Skripal's wife Lyudmila, 59, died in 2012 of uterine cancer, according to records from the National Health Service. His son Alexander, 43, died last year.

The authorities did not provide details, saying only that they had not exhumed any bodies, but the forensic activities at the London Road Cemetery intensified speculation about the poisonings.

Mr Skripal, 66, and daughter Yulia, 33, were found unconscious last Sunday afternoon on a bench outside a shopping centre in the southern English town. They remain in critical but stable condition.

The police have said they were poisoned with a nerve agent difficult to produce outside a government laboratory, heightening suspicions that Russia had played a role.

Last Friday, army experts and scores of troops were deployed to Salisbury to assist in the investigation. The 180 military personnel dispatched included the Royal Tank Regiment, Royal Marines and chemical weapons specialists.

AGENCE FRANCE-PRESSE, NYTIMES