President Donald Trump has ordered the expulsion of 60 Russian diplomats, leading to a massive and co-ordinated response to Moscow’s alleged involvement in the poisoning of a former Russian spy in the UK.

The collective expulsion of 100 Russian diplomats includes 20 European countries and Canada.

The US expulsion is the toughest action taken by Mr Trump against Russia, following what one official called a “reckless attempt” by the Russian government on March 4 to attack former spy Sergei Skripal and his daughter Yulia with a military-grade nerve agent.

The President also closed the Russian consulate in Seattle.

“Today’s actions make the United States safer by reducing Russia’s ability to spy on Americans and to conduct covert operations that threaten America’s national security,” White House spokesperson Sarah Huckabee Sanders said.

“With these steps, the United States and our allies and partners make clear to Russia that its actions have consequences,” she said.

British Prime Minister Theresa May called the co-ordinated move by 21 countries the largest collective expulsion of Russian intelligence officers in history.

The Australian government later expelled two Russian diplomats described as undeclared spies.

The officials will have to leave the country within seven days, Prime Minister Malcolm Turnbull and Foreign Minister Julie Bishop said in a joint statement on Tuesday.

UK Foreign Secretary Boris Johnson praised the “extraordinary international response” by Britain’s allies.

Today’s extraordinary international response by our allies stands in history as the largest collective expulsion of Russian intelligence officers ever & will help defend our shared security. Russia cannot break international rules with impunity

— Boris Johnson (@BorisJohnson) March 26, 2018

Moscow has denied responsibility for the attack and has retaliated against Britain’s expulsion of 23 Russians earlier this month by ordering out the same number of Britons.

Russia has vowed to retaliate against the new “provocative gesture” by each country accordingly.

The attack on the Skripals was the first known offensive use of a nerve toxin in Europe since World War II, and European Union member states agreed on Friday to take additional measures against Russia.

The Seattle consulate on the west coast state of Washington was selected for closure because of its proximity to a US submarine base and to plane-maker Boeing Co, the US officials said.

Mr Trump’s order also included 12 Russians described by the US officials as Russian intelligence officers from Russia’s mission to the United Nations headquarters in New York. This reflects US concerns that Russian intelligence activities have been increasingly aggressive.

The US officials said Russian diplomats have been abusing their diplomatic privileges in the US and across the world.

“They hide behind the veneer of diplomatic immunity while actively engaging in intelligence operations that undermine the country in which they are hosted in a democracy they seek to minimise,” an official said.

“With today’s action, we are removing a large number of the unacceptably numerous Russian intelligence officers who abide in the United States,” the official said.

-with AAP