Countries across Europe are preparing to expel Russian diplomats as the fallout over the poisoning of a former double agent in Salisbury reached unprecedented levels.

At least six countries are understood to be considering the expulsion of Russian spies after the EU took the lead and announced it would recall its ambassador to Moscow.

In an indication of a possible escalation in the EU response, French President Emmanuel Macron said France and Germany would be among the countries taking "co-ordinated measures" against Russia, with an announcement due "very shortly".

Leaders from across the bloc backed Theresa May’s claim that the Kremlin was “highly likely” to be responsible for this month’s nerve agent attack in Salisbury.

In a joint statement in the early hours of yesterday, EU leaders said there was “no plausible alternative explanation” for the use of novichok in Salisbury other than its deployment by the Russian government.

The EU said its ambassador had been recalled “for consultations” following the incident.

It is understood that at least Ireland, France, Estonia, Poland, Latvia and Lithuania are considering the expulsion of the Russian diplomats, following the UK’s decision to expel 23 staff, including alleged undeclared intelligence officers. Others could follow suit after consultations over the weekend

Those countries taking the lead on the issue are those in the east most wary of Russian interference, and Britain’s closest neighbours and traditional allies.

Speaking at a press conference in Brussels on Friday European Council president Donald Tusk would not be drawn on the exact number of member countries who would expel diplomats, saying he believed the final count would be “more than one, but I don’t think it will be the whole group”.

Irish Taoiseach Leo Varadkar said: “What we’ll now consider in the coming days is whether we want to take individual action relating to Russian diplomats in Ireland, bearing in mind what the UK did was to expel 23 diplomats, who they did not believe were diplomats, they were agents.

“We would have to do a security assessment before we did that. We’re not just going to randomly expel people who are genuine diplomats.”

Ms May urged leaders at a dinner of the European Council to go further than their foreign ministers had on Monday, when the bloc said that they took the assessment of Russian responsibility “extremely seriously”.

Dmitry Peskov, Vladimir Putin’s spokesman, said Russia “doesn’t understand” the EU’s decision, and said Moscow would need to study the exact measures being taken by the bloc before it could respond.

The Kremlin said the UK was forcing its allies to take “confrontational steps” over the incident. Russia denies any involvement in the poisoning.

Mr Peskov said: “We don’t know what info the UK had when it discussed with EU colleagues. We don’t understand it.

“Russia has not had the opportunity to receive a diagnosis [on the Skripals]. Regarding the EU decision, we are unhappy with ‘highly likely’ formulations. Russia categorically has nothing to do with the Skripal [poisoning].”

Vladimir Putin dismisses 'nonsense' of Russian involvement in Salisbury poisoning

Speaking on the doorstep of the summit in the small hours of the morning after the dinner, Ms May said: “We’ve had a very full discussion on Russia at this EU Council and I welcome the fact that the EU Council has agreed with the UK Government’s assessment that it is highly likely that Russia was responsible for the attempted murder that took place on the streets of Salisbury, and that there is no plausible alternative explanation.

“Russia, and the threat that Russia poses, respects no borders and that is a threat to our values and it is right that here in the EU Council we are standing together to uphold those values.”

Former Russian intelligence officer Sergei Skripal and his daughter, Yulia, remain in a critical condition following the 4 March attack in Salisbury.

The joint statement by the European Council says: “The European Council condemns in the strongest possible terms the recent attack in Salisbury, expresses its deepest sympathies to all whose lives have been threatened and lends its support to the ongoing investigation.

“It agrees with the UK Government’s assessment that it is highly likely that the Russian Federation is responsible and that there is no plausible alternative explanation. We stand in unqualified solidarity with the United Kingdom in the face of this grave challenge to our shared security.

“The use of chemical weapons, including the use of any toxic chemicals as weapons under any circumstances, is completely unacceptable, must be systematically and rigorously condemned and constitutes a security threat to us all.