VARIED RESPONSES

At the same UN meeting, US Ambassador Nikki Haley said the Trump administration "stands in absolute solidarity" with Britain following the incident.

The United States believes that Russia "is responsible for the attack" on the two using a military-grade nerve agent, Haley added.

The White House issued a statement on the day in support of Britain, saying London's decision to expel the Russian diplomats was justified.

"The United States stands in solidarity with its closest ally, the United Kingdom," and is working together with its allies and partners to ensure that "this kind of abhorrent attack does not happen again," the White House said.

It noted that the incident "fits into a pattern of behavior in which Russia disregards the international rules-based order, undermines the sovereignty and security of countries worldwide, and attempts to subvert and discredit Western democratic institutions and processes."

France said it would not take any position on the issue before "the facts are fully proven."

Asked whether France was ready to retaliate as part of a common European stance to support Britain, French Government spokesperson Benjamin Griveaux told reporters after a weekly cabinet meeting, "we do not do politics-fiction over serious and sensitive issues. Once the elements will be proven, decisions will be taken."

He also said: "What happened in Britain is a very serious act ... Britain is France's strategic and historical ally."

Ma Zhaoxu, the Chinese ambassador to the UN, said China hopes that "a comprehensive, objective and impartial investigation" will be conducted based on facts and in accordance with relevant international rules, reaching an evidence-based conclusion "that can stand the test of facts and history."

Speaking at a daily brief on Wednesday, a deputy spokesperson of UN Secretary General Antonio Guterres expressed concern over the poisoning incident.

"The secretary-general is deeply concerned over the reported use of a nerve agent in the United Kingdom to harm or kill persons," Farhan Haq said.

"The use of nerve agents as a weapon under any circumstances is unacceptable and its use by a state will constitute a serious violation of international law."

Haq also said while the secretary general was not in a position to attribute responsibility for the attack, he strongly condemned the use of any nerve agent or chemical weapons and hoped the incident would be thoroughly investigated.