President Donald Trump will expel dozens of Russian diplomats from the U.S. in retaliation for the poisoning of former spy Sergei Skripal and his daughter in the U.K.

Two people close to the Trump administration told Bloomberg on Saturday the president has agreed to take the advice he received from the National Security Council and proceed with the expulsions.

However, the anonymous sources warned that the president could still change his mind before Monday, when the announcement is expected, as he wants to make sure European allies are also taking action on the matter.

Two people close to the Trump administration told Bloomberg the president has decided to expel dozens of Russian diplomats in retaliation for the poisoning of an ex-spy

Former spy Sergei Skripal and his daughter remain in critical condition after they were poisoned with the highly lethal nerve agent Novichok on March 4

Trump allegedly discussed the issue on Friday with the U.S. Ambassador to Russia Jon Huntsman, Attorney General Jeff Sessions, Defense Secretary James Mattis and National Security Adviser H.R. McMaster, among others.

Deputy White House Press Secretary Raj Shah said on Saturday: 'The United States stands firmly with the United Kingdom in condemning Russia's outrageous action.

'The president is always considering options to hold Russia accountable in response to its malign activities. We have no announcements at this time.'

The diplomats in question are considered undercover spies who disguise as embassy staff to carry out intelligence activity, one of the aides cited by Bloomberg said.

Trump allegedly discussed the issue on Friday with the U.S. Ambassador to Russia Jon Huntsman, and National Security Adviser H.R. McMaster (pictured with Trump), among others

May has already ordered the expulsion of 23 Russian diplomats she claimed were undeclared spies working at the London embassy

Skripal and his daughter, Yulia, remain in critical condition after they were poisoned with the highly lethal nerve agent Novichok on March 4.

Prime minister Theresa May has said its 'highly likely' the Kremlin is behind the poisoning, a statement the American, French and German governments have agreed with.

Russia has vehemently denied any responsibility for the poisoning.

'As soon as we get the facts straight … if we agree with them, we will condemn Russia or whoever it may be,' Trump said after facing criticism for refusing to name Russia as the likely aggressor.

May has already ordered the expulsion of 23 Russian diplomats she claimed were undeclared spies working at the London embassy.

Last week, EU leaders promised an 'unprecedented' diplomatic response to the attack. According to the Times of London, the coordinated campaign will start with the recall of the European Union's ambassador to Russia for four weeks on Monday.

The EU's coordinated campaign will start with the recall of the European Union's ambassador to Russia for four weeks on Monday (pictured is ambassador Markus Florian Ederer)

Both Democrats and Republicans expressed disappointment earlier this week after Trump congratulated Vladimir Putin on his electoral win, arguing that the Russian leader did not allow free and fair elections.

Trump has repeatedly stated he intends to have a good personal relationship with Putin, and on Wednesday tweeted those who wanted him to 'excoriate' Putin over the allegedly unfair elections were 'wrong!'.

'Getting along with Russia (and others) is a good thing, not a bad thing,' he added.

The president has recently replaced National Security Adviser McMaster with former ambassador to the United Nations John Bolton and Secretary of State Tillerson with CIA Director Mike Pompeo, changes that could impact his administration's stance towards Russia.