The Russian embassy has requested a meeting with Boris Johnson to discuss the attack on the former double agent Sergei Skripal and his daughter, Yulia, saying that its dealings with Britain over the issue had been “utterly unsatisfactory”.

The Foreign Office confirmed that a request had been received, but a spokeswoman countered that it was Russia’s response to the incident that had been unsatisfactory. She accused its diplomats of a new “diversionary tactic”.

The two countries have been embroiled in a propaganda war since Skripal and his daughter were found seriously ill on a park bench in Salisbury, Wiltshire, just over a month ago. After it was established that they had been poisoned, the UK government accused Russia of an attempted assassination.



However, Russia gained the upper hand scored a PR victory this week when the chief executive of the UK’s chemical weapons laboratory undermined claims by Boris Johnson, the foreign secretary, that there was scientific evidence that the poison was made in Russia. The government has since claimed that it has separate intelligence that traces the poison used, described by scientists as being from the novichok family of nerve agents, back to Russia.

Quick guide What is novichok? Show Hide Novichok refers to a group of nerve agents developed by the Soviet Union in the 1970s and 80s to elude international restrictions on chemical weapons. Like other nerve agents, they are organophosphate compounds, but the chemicals used to make them, and their final structures, are considered classified in the UK, the US and other countries. The most potent of the novichok substances are considered to be more lethal than VX, the most deadly of the familiar nerve agents, which include sarin, tabun and soman. Novichok agents work in a similar way, by massively over-stimulating muscles and glands. Treatment for novichok exposure would be the same as for other nerve agents, namely with atropine, diazepam and potentially drugs called oximes. The chemical structures of novichok agents were made public in 2008 by Vil Mirzayanov, a former Russian scientist living in the US, but the structures have never been publicly confirmed. It is thought they can be made in different forms, including as a dust aerosol. The novichoks are known as binary agents because they only become lethal after mixing two otherwise harmless components. According to Mirzayanov, they are 10 to 100 times more toxic than conventional nerve agents. Photograph: Matt Cardy/Getty Images Europe

In a statement posted on its website, the Russian embassy said: “We believe that it is high time to arrange a meeting between ambassador Alexander Yakovenko and foreign secretary Boris Johnson in order to discuss the whole range of bilateral issues, as well as the investigation of the Salisbury incident.

“Ambassador Yakovenko has already sent a respective personal note to the foreign secretary. We hope that the British side will engage constructively and that such meeting is arranged shortly.”

The FCO’s spokeswoman said: “It’s Russia’s response that has been unsatisfactory. It’s over three weeks since we asked Russia to engage constructively and answer a number of questions relating to the attempted assassinations of Mr Skripal and his daughter.

“Now, after failing in their attempts in the UN and international chemical weapons watchdog this week and with the victims’ condition improving, they seem to be pursuing a different diversionary tactic. We will of course consider their request and respond in due course.”

Play Video 0:59 Sergei Skripal responding well to treatment, says Salisbury hospital – video

The hospital where the Skripals were being treated said on Friday that they were both recovering. Their testimony could be crucial in establishing the credibility of the government’s claim that it was “highly likely” Russia targeted them.

The Kremlin’s strategy has been to exploit weaknesses and inconsistencies in the UK’s case. This week it has seized on a blunder by Johnson, who wrongly claimed that the government science facility at Porton Down had definitively attributed the nerve agent to Russia. The UK government’s embarrassment was compounded when the Russian embassy caught the FCO deleting tweets that made the same claim.

Meanwhile, the Home Office has confirmed that Sergei Skripal’s niece, Viktoria, has been denied a visa to visit the UK from Russia, saying her application did not comply with immigration rules. She emerged as part of the affair with a bizarre television appearance during which she played what was said to be a recording of a telephone conversation with Yulia Skripal. Its authenticity has not been confirmed.