Foreign Ministers from EU member states condemned Russia over its alleged attempted poisoning of an ex-spy and his daughter in the UK, as they gathered for a council meeting in Brussels on Monday.

Sergei Skripal, 66, and his daughter Yulia remain in critical condition after being reportedly poisoned by a substance believed to be Novichok, a type of nerve agent developed by Russia, an event which has caused a rift between Moscow and London as each accused the other of being behind the alleged attack.

“The EU is shocked at the offensive use of any military-grade nerve agent, of a type developed by Russia, for the first time on European soil in over 70 years,” the European Council said in a statement cited by Efe news.

Just before a meeting chaired by EU’s foreign policy chief Federica Mogherini, British Foreign Secretary Boris Johnson said Russia’s explanations were “growing increasingly contradictory and absurd”, which was “a common Russian strategy of trying to conceal their needle of truth in a haystack of lies and obfuscation”.

Moscow would at one moment claim they never had Novichok or that they had some in the past but it had been destroyed, or that some had been secretly saved and smuggled to Sweden or the Czech Republic or even the US and the UK, he said.

Russian authorities had even accused the UK of preparing the attack on its own soil to promote anti-Russian sentiments in the West, but Johnson insisted that, after the poisoning of former spy Alexander Litvinenko in London in 2006, “they are not fooling anybody anymore”.

Spain’s top diplomat Alfonso Dastis said a common declaration was set to be prepared during the council meeting to show support for the UK and ask Moscow to clarify how the substance made it to the country, but there were still many details that needed to be cleared up.

He refused to clarify whether his country would back applying sanctions on Russia, saying: “We will see that when the whole situation is cleared up We think now the time is for an extended examination of all the elements involved with the participation of the Organization for the Prohibition of Chemical Weapons (OPCW).”

Technicians from the OPCW were set to travel to Salisbury later on Monday to collect samples of the substance used on Skripal and several EU countries have insisted that their investigation was central to any decision-making related to a response to Russia.

UK Prime Minister Theresa May on Wednesday ordered the expulsion of 23 Russian diplomats who were identified as “undisclosed intelligence officers” in retaliation for the alleged poisoning, a move that Moscow mirrored a few days later.

Mogherini said the meeting would also include debriefings on potential upcoming talks between the US and North Korea and the situation in Syria as well as a discussion on Iran.