THE HAGUE (AFP) - Diplomats were holding emergency talks on Wednesday (April 18) on the poisoning of a former Russian spy, after the global chemical arms watchdog confirmed British findings that he was the victim of a nerve agent attack.

Diplomatic sources said the closed-door meeting of the Organisation for the Prohibition of Chemical Weapons (OPCW) had begun at its headquarters in The Hague.

It was the second meeting of the body's executive council in three days, and was called by Britain to discuss the findings of the investigation into the poisoning of former Russian double agent Sergei Skripal and his daughter last month in the British town of Salisbury.

After deploying its experts to Salisbury, the OPCW last week issued a report, saying it confirmed "the findings of the United Kingdom relating to the identity of the toxic chemical".

It did not however publicly name the substance, which Britain says was a Novichok nerve agent of the sort first developed in the Soviet Union in the 1970s.

In a letter requesting Wednesday's talks, the British delegation to the OPCW said it wanted "to brief state parties" on the events.

AFP saw the British ambassador Peter Wilson and his aides arriving at the OPCW headquarters, as well as top Russian, American and French diplomats.

Russia has angrily denied being behind the March 4 attack on the Skripals, and the crisis, coupled with Russian support for its ally Syria, has sent frayed relations between Moscow and the West plummeting to new lows.

On Monday, the OPCW's governing executive council also met in secret to discuss its inspectors' risky mission to the Syrian town of Douma to probe allegations of a chemical gas attack on April 7.

London said on Tuesday the nerve agent substance used in Salisbury had been delivered in "liquid form" and in small quantities.

A meticulous cleanup has now begun in Salisbury, and the town's cemetery where Skripal's wife and son are buried was reopened on Tuesday.

But nine other sites, including a pub and a restaurant the Skripals visited shortly before collapsing, remain closed off and the work could take several months.

Suspected sites are tested, items which may have been contaminated are removed for chemical cleaning and then re-testing, Britain's environment ministry said.

The Skripals were found slumped on a bench in Salisbury, having earlier visited a pub and a restaurant.

Sergei Skripal, 66, remains in the city's hospital, though he is improving rapidly and no longer in a critical condition, doctors said in their last update on April 6.

Yulia Skripal, 33, who had been visiting her father in England when the attack took place, has been discharged and is continuing her recovery in a safe house.

The Group of Seven industrial powers condemned the attack "in the strongest possible terms" on Tuesday.

They agreed it was "highly likely" that Russia was responsible and there was "no plausible alternative explanation".