EU blames Moscow for UK spy attack, recalls envoy

European Union leaders united behind British Prime Minister Theresa May on Thursday in blaming Russia for a nerve agent attack in England, and agreed to recall their ambassador to Moscow for consultations.

Some states are now considering following Britain's lead in expelling Russian diplomats, with Lithuania and France among those indicating a willingness to take action.

British Prime Minister Theresa May had pressed the importance of a united response to the March 4 poisoning of former double agent Sergei Skripal and his daughter Yulia in the English city of Salisbury.

At a summit in Brussels, the 28 EU leaders offered her their full support, agreeing "that it is highly likely that the Russian Federation is responsible and that there is no plausible alternative explanation".

They pledged to "coordinate on the consequences", and Dutch Prime Minister Mark Rutte said they had agreed to recall the bloc's ambassador to Moscow for consultations.

"Some member states are looking into possibly expelling Russian diplomats or recalling national diplomats," an EU official added.

Moscow strongly denies any involvement but London has identified the chemical used as the Soviet-designed Novichok, and says Russia had the means and the motive to carry out the attack.

May emphasised to EU leaders that it came as part of a "pattern of Russian aggression" and warned Moscow would pose a threat for "years to come" -- long past Britain's exit from the bloc in March next year.

"The threat that Russia poses respects no borders and it is a threat to our values," she said after briefing fellow leaders over dinner.

"It is right that here in the EU council we are standing together to uphold those values."

The Skripals are both in a coma after they were found collapsed on a park bench, although a policeman who was also contaminated was released from hospital on Thursday.

Diplomatic expulsions

The United States, France and Germany offered early backing for the conclusion that Moscow was to blame for the first offensive use of a nerve agent in Europe since World War II.

But Britain's efforts to win a tough line from all 28 EU members ran up against countries keen to protect their Kremlin ties, notably Greece and Italy.

May met French President Emmanuel Macron and German Chancellor Angela Merkel shortly before the dinner, and both called for a "strong European message", their offices said.

"We had an in-depth, very long discussion and said in a very unified way that it was highly likely that Russia was behind the attack, that there could not be another explanation," Merkel said after the meeting of all 28 leaders.

The poisoning has heightened worries across Europe about Russian meddling -- from repeated cyber attacks to what the EU has called an "orchestrated strategy" of disinformation aimed at destabilising the bloc.

Britain expelled 23 Russian diplomats they said were spies, and has been pressing EU allies to follow suit.

Lithuania's outspoken President Dalia Grybauskaite said: "All of us we are considering such measures."

A French presidency source earlier said Paris was also ready to act.

"Some countries, like France, are ready for possible measures to be decided at a national level in cooperation with other European countries," the source said.

London also suspended high-level diplomatic contacts, including an official-level boycott of the World Cup football tournament in Russia this summer.

Moscow expelled its own diplomats and halted the activities of the British Council cultural organisation.

The Kremlin has angrily rejected Britain's claims and Russian state media have offered numerous alternative explanations, including that London directed the attack itself.

Russian President Vladimir Putin convened a meeting of his national security council on Thursday to discuss "Britain's hostile and provocative policy towards Russia", according to a Kremlin statement.

'Never the same'

Authorities have yet to disclose exactly how Skripal and his daughter were poisoned, although dozens of people in the area were assessed by medics for possible contamination.

Local policeman Nick Bailey was hospitalised following the incident but was released on Thursday.

"Normal life for me will probably never be the same," he told reporters.

Britain believes it knows the exact type of chemical used and where it came from, but has called in experts from the Organisation for the Prohibition of Chemical Weapons to test its samples, as required by international law.

Their tests, which a British judge ordered Thursday could include samples of blood from Skripal and his daughter, are expected to take at least a fortnight.