A sign for the Russian Embassy is seen in Washington, D.C., on March 26, 2018. (Xinhua/AFP)

WASHINGTON, March 26 (Xinhua) -- U.S. President Donald Trump has ordered the expulsion of 60 Russian diplomats and intelligence officials, and the closure of the Russian Consulate in Seattle in response to the poisoning of a Russian ex-spy in Britain earlier this month.

The Russian officials, including 12 from the Russian mission at the United Nations, were asked to leave the United States within seven days, senior U.S. officials said Monday, speaking on condition of anonymity.

"The United States takes this action with NATO allies and partners around the world in response to Russia's use of military-grade chemical weapon on the soil of the United Kingdom," said the officials.

European Council President Donald Tusk announced Monday in Varna, Bulgaria that 14 member states of the European Union have also decided to expel Russian diplomats.

Sergei Skripal, 66, a former Russian intelligence officer, and his 33-year-old daughter Yulia were found unconscious on a bench at a shopping center in Salisbury on March 4.

British police officers stand on duty as members of the Army work in a residential street in Alderholt, southern England, on March 15, 2018, as investigations and operations continue in connection with the major incident sparked after a man and a woman were apparently poisoned in a nerve agent attack in Salisbury on March 4. (Xinhua/AFP)

They remain in critical condition after exposure to a nerve agent, which, according to the British authorities, could have originated from Russia.

Moscow has denied any involvement in the incident and insisted on participating in direct investigation into the case.

The Russian Foreign Ministry said Monday that Russia "strongly protests" diplomats expulsion by the United States and 14 European countries, vowing to retaliate.

Russia Ambassador to the United States Anatoly Antonov told reporters on Monday that Moscow will give adequate response to the U.S. expulsion decision.

Photo taken on March 14, 2018 shows a general view of United Nations Security Council's meeting on the poisoning of a former Russian spy in Britain at the UN headquarters in New York. (Xinhua/Li Muzi)

The White House said Monday in a statement that the closure of the Russian Consulate in Seattle was due to its proximity to one of the U.S. submarine bases and Boeing.

"With these steps, the United States and our allies and partners make clear to Russia that its actions have consequences," it noted.

On March 13, Trump spoke with British Prime Minister Theresa May over phone on the poisoning incident, vowing to "stands in solidarity with its closest ally and is ready to provide any assistance the United Kingdom requests for its investigation."

File Photo: U.S. President Donald Trump (L) and British Prime Minister Theresa May (R) attend the handover ceremony of the new NATO headquarters during a one-day NATO Summit, in Brussels, Belgium, May 25, 2017. (Xinhua/Ye Pingfan)

"It sounds to me like they believe it was Russia and I would certainly take that finding as fact," he added.

Following the incident, Britain has announced the expulsion of 23 Russian diplomats, freezing of Russian state assets, suspension of high-level bilateral contacts, and a boycott of this year's World Cup in Russia by ministers and royal family members. Moscow later expelled an equal number of British diplomats in response.

"The conclusion is obvious: it is another informational and political campaign based on a provocation," Russian Foreign Ministry Spokeswoman Maria Zakharova was quoted by Sputnik news agency as saying.