Russian agents may have deliberately left a bottle of the nerve agent novichok in Salisbury after the attempted assassination of the former spy Sergei Skripal as part of a campaign to undermine security in the UK, the high court has been told. Lawyers for the family of Dawn Sturgess, who died of novichok poisoning four months after the attack on Skripal, claim the actions of the agents on the ground and those who masterminded the plot from Moscow could have led to many hundreds of deaths. Sturgess’s family are arguing that the scope of the inquest into her death should be widened to examine the alleged role of the Russian state, claiming the poisonings were a matter of “almost unparalleled public concern”. Skripal and his daughter Yulia were the initial victims of a novichok attack on 4 March 2018 in the Wiltshire city of Salisbury. Both they and a police officer, DS Nick Bailey, who was also poisoned, survived. At the end of June 2018, Sturgess and her partner, Charlie Rowley, were poisoned in Amesbury, 8 miles north of Salisbury, after he found a fake perfume bottle containing novichok. Rowley recovered but Sturgess, 44, died on 8 July. Michael Mansfield QC, for the Sturgess family, described novichok as a “weapon of mass destruction” and said getting to the bottom of the attack was not just of national but of international interest and importance. The barrister flagged up mysteries surrounding the perfume bottle. He highlighted that the container Rowley found was secured in thick plastic. “Someone had taken the trouble to seal this up very tightly,” he said. Mansfield added that the way it was sealed meant it would have remained deadly for decades. Mansfield claimed it was unlikely that the bottle had for four months been in the bin where Rowley said he found it. He also told the high court that the inquest, likely to take place next year, should look at whether it was possible more novichok had been left in the UK. Two Russian agents, Alexander Petrov and Ruslan Boshirov, have been charged by the Crown Prosecution Service in the UK over the attack on the Skripals. The Wiltshire and Swindon senior coroner, David Ridley, accepted their role should be considered during Sturgess’s inquest but ruled that he would not look into wider claims about the part played by the Russian state. Challenging the decision, Mansfield said it was “inconceivable” that Petrov and Boshirov operated in “a bubble”. He said the operation must have been authorised by the Russian state – right up to President Vladimir Putin. The barrister referred to a statement by the then UK prime minister, Theresa May, in September 2018 in which she said: “This chemical weapons attack on our soil was part of a wider pattern of Russian behaviour that persistently seeks to undermine our security and that of our allies around the world.” Mansfield said it was possible that leaving the poison behind after the attack on Skripal had been an oversight, but he added: “An alternative, we say, is: was it deliberate? Was it left behind deliberately to be part of a pattern of behaviour alluded to by the prime minister?” He added: “The use of novichok in Salisbury was the first aggressive use of a nerve agent in Europe since the second world war. It put hundreds of members of the British public at risk and killed Ms Sturgess. The issue of who was responsible for it is a matter of almost unparalleled public concern.” The hearing continues.