According to government sources, the “show of solidarity” with the UK would involve the expulsion of a number of Russian diplomats in support of the UK over the Salisbury nerve agent attack on March 4.

Tánaiste Simon Coveney, following a security briefing, is to make a recommendation to Cabinet today and the Irish Examiner has confirmed that this will mean a number of Russian diplomats having to leave the country.

“Simon Coveney will bring a recommendation to Cabinet on Tuesday following a review and then the Cabinet will approve it,” said a source. “Ireland requires a Cabinet decision. It would not be unreasonable to expect that some form of expulsions are likely.”

This would be the most aggressive move by an Irish government since the 2010 expulsion of an Israeli diplomat over the use of forged passports in the assassination of a Hamas arms dealer in Dubai, allegedly by Israeli agents.

Mr Coveney was briefed last night and has been in constant contact with Leo Varadkar on the matter.

Formally, it is up to Mr Coveney to present a recommendation to Cabinet for its approval. His spokesman said the assessment of alleged Russian activities in Ireland by a high-level group was “ongoing”.

“Donald Tusk’s tweet does not include Ireland. Assessments on our side are continuing,” the spokesman said.

Yesterday, Mr Tusk, the European Council president, tweeted 14 EU member states had decided to expel Russian diplomats in response to the poisoning in the UK of former Russian spy Sergei Skripal and his daughter, Yulia.

Hungary later also expelled one diplomat. The US, Canada, Albania, Macedonia, and Ukraine have also ejected diplomats.

The co-ordinated move drew a furious response from Moscow, where president Vladimir Putin’s government described it as a “provocative gesture” that “continues the policy of escalating the confrontation”.

It is expected the Tánaiste will share his assessment of the situation in Ireland at this morning’s weekly Cabinet meeting, after which he and Mr Varadkar will indicate what sanction will apply. Sources said on Sunday that given the Taoiseach’s prominence in leading with this issue at the European Council in Brussels, it is highly likely at least one Russian diplomat will be expelled.

Such expulsions do not require a formal Cabinet decision and are executive decisions made by the Taoiseach of the day, on the recommendation of the minister for foreign affairs.