UK PM says Russia responsible for attack on ex-spy; expels 23 Russian diplomats

London: British Prime Minister Theresa May today held Russia responsible for the nerve agent attack against a former Russian spy and his daughter as she expelled 23 Russian diplomats and suspended high-level bilateral contact.

Former Russian spy Sergei Skripal, 66, and his daughter Yulia, 33, were found collapsed after being poisoned last week. Both remain in a serious condition along with a police officer who came in contact with the same substance.

Russia denies being involved in the attempted murder of the former spy and his daughter.

"The Russian state was culpable of the attempted murder" of spy Sergei Skripal and his daughter, May told lawmakers.

She said Britain will suspend high-level bilateral contact with Russia and revoke an invitation to Russian Foreign Minister Sergei Lavrov to visit the UK.

The Prime Minister announced that Britain will expel 23 Russian diplomats, saying they have one week to leave the UK.

She identified those diplomats as "undeclared intelligence officers", BBC reported.

Moscow, which had been given an ultimatum to provide a "credible response" over how a Russian-made nerve agent came to be used on British soil, had warned of "an equal and opposite reaction" against any UK reprisals.

The reprisals follow days of diplomacy since May first informed Parliament that there was enough evidence to conclude that it is "highly likely" that Russia is behind the poisoning of Skripal and his daughter in Salisbury on March 4.

"Russia's record of conducting state-sponsored assassinations; and our assessment that Russia views some defectors as legitimate targets for assassinations; the government has concluded that it is highly likely that Russia was responsible for the act against Sergei and Yulia Skripal," she had said.

"It was an indiscriminate and reckless act against the United Kingdom, putting the lives of innocent civilians at risk. And we will not tolerate such a brazen attempt to murder innocent civilians on our soil," she added, giving Moscow a Tuesday midnight deadline to respond on the circumstances surrounding the attack.

US President Donald Trump, as well as North Atlantic Treaty Organisation (NATO) and European Union (EU) allies including Germany's chancellor, Angela Merkel, have since come out in support of the UK and offered support.

Downing Street said the British prime minister received the backing of Trump, who agreed in a phone call that Moscow "must provide unambiguous answers as to how this nerve agent came to be used".

A spokesperson added that France's President Emmanuel Macron and German Chancellor Angela Merkel had also condemned the attack and offered support to the UK, as well as Estonia, Latvia and Lithuania – the Baltic states bordering Russia.

Russia, however, has insisted that it is being blamed unfairly, with the Russian embassy in the UK tweeting that the ambassador, who had been summoned to the UK Foreign and Commonwealth Office (FCO) for an explanation, had branded the actions of the UK authorities as a "clear provocation".

Russian Foreign Minister Sergei Lavrov has accused Britain of "playing politics" and ignoring an international agreement on chemical weapons. He had said Moscow would cooperate if it received a formal request for clarification from the UK under the Chemical Weapons Convention, which sets a 10-day time limit for a response.

Meanwhile, Skripal, and his daughter remain critically ill in hospital.

A former Russian military colonel, Skripal was convicted of treason in 2006 and jailed for 13 years for selling secrets to MI6, which had recruited him in the 1990s.

The senior intelligence officer with Russian military intelligence GRU, was pardoned in a spy swap in 2010 and settled in Salisbury, Wiltshire.

A week after he and his daughter were found collapsed on a bench of a shopping centre in the city, Britain's public health authorities had asked hundreds of people who were at a restaurant and pub linked with the poisoning of the Russian spy to clean up their possessions to remove any traces of the deadly nerve agent.

The poison used in the attack has been identified as belonging to a group of chemical nerve agents known as 'Novichok', which means "newcomer" and was used by the Soviet Union during the Cold War era in 1970s and 1980s.

Like most nerve agents, it has the effect of blocking messages from the nerves to the muscles in the body, which leads to a collapse of body functions and ultimately death by asphyxiation.