Many Russians believe a Western provocation was behind the nerve-agent poisoning of a former Russian spy in the UK, analysts say, as conspiracy theories about the attempted assassination flourish in the country.

British Prime Minister Theresa May's allegation that the Russian government's involvement was "highly likely" in the attempt to kill Sergei Skripal, 66, with the Novichok nerve agent on March 4 caused outrage in Russia, Dmitri Babich, a political analyst based in Moscow, told Al Jazeera on Tuesday.

"[The Russian public] simply does not believe that President [Vladimir] Putin or anyone in the Russian intelligence would order such a murky way of getting rid of this person - poisoning him in a public place with a highly dangerous substance," said Babich.

Skripal's poisoning was widely seen in Russia as a secret plan carried out by the British or American intelligence services in order to make Moscow look bad, he said.

Skripal and his daughter Yulia, 33, were discovered unconscious on a bench outside a shopping centre in Salisbury, in southern England.

Both are fighting for their lives in critical condition in a hospital.

According to the Tass news agency, the speaker of Russia's parliament, Vyacheslav Volodin, put the responsibility for the attack on the UK.

"The British Prime Minister Theresa May is very clumsy in trying to cast the suspicions away from the British side ... All the responsibility for the situation that involves our nationals who have left our country is on Britain," Volodin told reporters on Tuesday.

Sergei Markov, director of the Moscow-based Institute of Political Studies, was more direct and accused May of using the scandal to deflect public attention from the internal problems her government is facing, including Brexit.

"Theresa May has a lot of problems because of the failure in the parliamentary elections, Brexit, and the complicated situation with the border between Ireland and the Northern Ireland," Markov told Al Jazeera.

"So the British intelligence service probably organised the killing of Mr Skripal, sacrificing the guy who they don't need any more."

The British claim that the Novichok nerve agent was only accessible to the Russian government was untrue, he added.

"Novichok had been produced in Uzbekistan in the Soviet times and after the fall of the Soviet Union, as we know, the American intelligence services had access to this factory." Sergei Markov, director of Institute of Political Studies

"Novichok had been produced in Uzbekistan in the Soviet times and after the fall of the Soviet Union, as we know, the American intelligence services had access to this factory," Markov said.

"The American and British intelligence services have a very strong cooperation with each other, and I am sure 100 percent that the British got this Novichok nerve agent from them for this provocation."

He alleged Washington and London were working together to check Russia's global power.

British ultimatum

Skripal was a colonel in Russian military intelligence when, in 1995, he sold information to the UK. He left the Russian service in 2000, but was arrested and sentenced in 2006 to 13 years in prison for espionage.

In 2010, Skripal was pardoned and allowed to move to London after the British and Russian governments exchanged captured spies.

On Monday, May said Skripal's poisoning was either "a direct act by the Russian state against our country, or the Russian government lost control of its potentially catastrophically damaging nerve agent and allowed it to get into the hands of others".

London gave Moscow until the end of Tuesday to explain the attack, and said it would deliver a new statement on Wednesday.

Russia responded on Tuesday saying it would answer only if the UK gave Moscow access to the investigation material.

Follow Al Jazeera's Tamila Varshalomidze on Twitter: @tamila87v