WASHINGTON, March 13 (Xinhua) -- The White House announced Tuesday that U.S. President Donald Trump spoke earlier with British Prime Minister Theresa May over phone on the poisoning attack in Britain.

In an announcement, the White House said the two leaders discussed Britain's investigation into "the chemical weapon attack on a private citizen and his daughter on British soil."

Trump said that the United States "stands in solidarity with its closest ally and is ready to provide any assistance the United Kingdom requests for its investigation."

He also agreed with May that the Russian government "must provide unambiguous answers regarding how this chemical weapon, developed in Russia, came to be used in the United Kingdom."

The two leaders agreed on the need for "consequences" for using chemical weapons in violation of international norms.

Earlier in the morning, Trump told the media that "it sounds to me like it would be Russia based on all of the evidence they have."

When asked if there should be a U.S. response, Trump said that "as soon as we get the facts straight... we will condemn Russia or whoever it may be."

Claiming that Moscow was "highly likely" responsible for the attack, May on Monday told the parliament that Russia's ambassador in London had been summoned to explain whether it was "a direct action by the Russian state" or the result of it "losing control" of its stock of nerve agents.

May said the attack, targeting Sergei Skripal and his daughter Yulia in London on March 4, involved a military-grade nerve agent of a type developed by Russia.

Her comments came after Skripal and his daughter, who remain in a critical but stable condition, had been found collapsed on a bench in London.

On Monday, the Kremlin's spokesman Dmitry Peskov denied Russian involvement in the incident.

Russian Foreign Ministry Spokeswoman Maria Zakharova also said May's statement about the alleged Russian trace in the attack was a "circus."

"The conclusion is obvious: it is another informational and political campaign based on a provocation," Zakharova was quoted by Russian media outlet Sputnik as saying.