Eleven EU countries have so far failed to join the others in expelling Russian diplomats in solidarity with the UK.
The list as of Tuesday (March 27) included Austria, Belgium, Bulgaria, Cyprus, Greece, Ireland, Luxembourg, Malta, Portugal, Slovakia, and Slovenia, EUobserver wrote.
Some of them are likely to join the EU mainstream in the next few days.
Belgium is still weighing up who to target from the 140 Russian diplomats accredited to Russia's bilateral mission to the country as well as its EU and NATO embassies.
The Irish foreign minister, Simon Coveney, promised on Monday to "take appropriate action" to "show solidarity with our closest neighbor" later on Tuesday.
The Slovak foreign ministry said: "The development of the situation, as well as Russia's response to the calls addressed to it by the EU countries – including Slovakia – will influence the next steps that we are prepared to consider in this case".
Portugal does not plan to expel anyone, saying it preferred action at the level of the EU28, instead of making bilateral moves or joining EU sub-groups.
"Portugal believes that coordination at the European Union level is the most effective means to respond to the gravity of the current situation," its foreign ministry said on Monday.
A spokeswoman for the Luxembourg foreign ministry told EUobserver: "Our government first wants to await the conclusions of the OPCW's analysis", referring to an international body on chemical warfare that is investigating the UK incident.
"There are only a few Russian diplomats in Luxembourg, with no proof that any of them are involved in spying activities," she added.
"Luxembourg has currently two diplomats in Moscow. If Luxembourg would expel two Russian diplomats, and Russia would expel two Luxembourg diplomat as a retaliatory measure, our embassy in Moscow would be closed … as our government always favored to maintain a dialogue with Russia, that would then become very difficult," she said.
Other EU states, who have a history of strong ties with Moscow, have also said they do not intend to expel Russian diplomats despite having signed up to an EU statement blaming Russia for a chemical weapon attack in England earlier this month.
"We will not take any national measures," Austrian chancellor Sebastian Kurz and foreign minister Karin Kneissl said in a joint statement.
"Indeed, we want to keep the channels of communication to Russia open. Austria is a neutral country and sees itself as a bridge-builder between East and West," they said.
The Austrian ruling coalition contains the far-right Freedom Party, which has signed a cooperation agreement with the ruling United Russia party in Moscow.
The Maltese government, which has made hundreds of millions of euros from selling EU passports to wealthy Russians, echoed Luxembourg.
It said in a statement: "We are not doing so ourselves [expelling Russian diplomats] because our diplomatic mission in Moscow is very small and any response by Russia would effectively terminate diplomatic relations."
"This operational decision does not reduce our support for the UK and our security partners", it said.
Bulgaria, which has strong business ties with Russian firms, cited the fact it is holding the rotating EU presidency as a need to maintain neutrality.
Greece, where the ruling coalition also contains a pro-Russian far-right party, called Anel, said previously it would never sanction a member of the UN permanent security council and that it wanted to see more evidence on what had happened in the UK.
Its foreign ministry declined to comment to EUobserver on Tuesday.
Cyprus, whose banks hold billions of euros in Russian capital and which has also been selling EU passports to wealthy Russians, followed Greece.
Slovenian foreign minister Karl Erjavec, who hosted Russia's foreign minister in February to try to boost business ties, said on Monday that it was too soon to decide on action because it must be first determined what exactly had happened in the UK.
The group of Russia-friendly EU states normally includes Hungary, which is planning to build a nuclear power plant with Russia.
But Budapest opted to expel one Russian diplomat anyway, joining the other 15 EU states who expelled 31 diplomats in total, and the UK itself, which expelled 23 of them.