Britain has asked the world's chemical warfare watchdog to extend its help in probing the death of a British woman allegedly exposed to the Novichok nerve agent, the Hague-based body said Tuesday.
"The Organisation for the Prohibition of Chemical Weapons received a request" from Britain on Monday "to extend its technical assistance in the technical evaluation of unscheduled chemicals," the OPCW said.
"In response to the request, the OPCW will deploy a technical assistance team for a follow-up visit and to collect additional samples," it added in a statement.
London asked the watchdog body last month to send a technical team to "independently determine the nature of the substance that is alleged to have resulted in the death of one person and left another person seriously ill" in Amesbury, in southern Britain.
Dawn Sturgess, a 44-year-old mother of three died after she handled what she thought was a bottle of perfume, given to her by her partner Charlie Rowley.
Both fell ill in Amesbury, near the southwestern English city of Salisbury where a former Russian spy and his daughter were also poisoned by Novichok in March, but survived.
Sturgess and Rowley were hospitalised on June 30 and a few days later authorities confirmed their exposure to Novichok, a military-grade nerve agent developed by the Soviet Union during the latter days of the Cold War.
Sturgess died eight days later, but after two weeks in an induced coma Rowley was discharged from hospital late last month.
Police are treating Sturgess' death as murder and say a link with the poisoning of Sergei Skripal and his daughter Yulia on March 4 is a major line of inquiry.
Britain and its allies blamed Russia for trying to kill Skripal, a former military intelligence colonel who was jailed for betraying Russian agents to Britain and who moved there in 2010 in a spy swap.
Russia has strongly denied involvement, sparking a major diplomatic row.
Emergency services personnel in green biohazard suits investigate the Novichok nerve agent poisoning in the southern British town of Salisbury