Russia’s British embassy has reiterated Moscow’s refusal to heed the deadline set by UK PM Theresa May to explain what she claims was an alleged Soviet-era military-grade toxic agent used to poison former Russian double agent Sergei Skripal and his daughter in Salisbury.

Russia has requested samples of the toxin. “Russia will not respond to London’s ultimatum until it receives samples of the chemical substance,” an embassy spokesman told Reuters, as the deadline to issue a clarification expired. In the statement on its website on Tuesday, the embassy said that if the UK is looking forward to receiving any information regarding the agent from Russia, it should enforce the appropriate mechanism provided by the Article 9 of the Chemical Weapons Convention. “We would also like to emphasize that such clarifications under the Convention are provided to the requesting member state as soon as possible, but in any case no later than 10 days following receipt of the request,” the embassy stated, noting that “the ultimatum’s demand that information be provided immediately” is “absolutely unacceptable.”