The chemical used in the attack has been identified part of a group of nerve agents developed by Russian Federation known as Novichok, Mrs May said.
"Russia'sresponse doesn't change the facts of the matter - the attempted assassination of two people on British soil, for which there is no alternative conclusion other than that the Russian State was culpable", a spokesperson said.
Johnson said Britain's National Security Council will meet this week to discuss what further measures the country might take.
"We can not sit back and let events overtake us".
Moscow announced the measures on the eve of a presidential election which incumbent Vladimir Putin should comfortably win.
They remain critically ill in hospital after the two were found unconscious on a bench in Salisbury, Wiltshire on 4 March.
The poisoning, which is being investigated as attempted murder by authorities, has plunged Britain and Russian Federation into a political crisis.
Russian Federation is to expel 23 British diplomats amid tensions over the nerve agent attack on a former spy and his daughter in the UK. Critics of the British government have long claimed that the U.K.is reluctant to act against Russia because London's property market and financial sector are magnets for billions in Russian money.
U.K. Defense Secretary Gavin Williamson called relations between the two countries "exceptionally chilly" and said Russian Federation should "go away and shut up".
People celebrate Marathi New Year Gudi Padwa Not only Maharashtra but other states in India like Karnataka and Andhra Pradesh also celebrate the day with much fanfare. Rajya Sabha member and AIFF president Praful Patel wished the nation on the occasion of Gudi Padva, Ugadi and Navratri.
British Foreign Secretary Boris Johnson has accused Russian PresidentVladimir Putin of personally ordering the poisoning.
But Russia maintains it has never made them.
Moscow has now also opened their own investigation into the attack on Yulia, who is a Russian citizen.
He said: "Those who are trying to complicate the organisation of the World Cup in Russian Federation have a motive in the Skripal case".
Major General Igor Konashenkov, a spokesman for the Russian Defense Ministry, shot back that Williamson's comments reflected a "high degree of his intellectual impotence, " adding: "The boorish language is apparently the only thing left in the British military arsenal".
Russia's Defence Ministry called UK Defence Secretary Gavin Williamson a "vulgar old harpy" on Thursday, after he said the country should "shut up" and "go away".
Asked by a Reuters reporter in the Kazakh capital if Russia planned to expel British diplomats from Moscow, Russian Foreign Minister Sergei Lavrov smiled and said: "We will, of course".
The leaders did not say what, if any, actions they would take if Russian Federation does not comply.
The condition of the pair has been described as critical but stable.
Werdum then stood on the chair to look down on Volkov who usually towers above him. "I knew that his jiu-jitsu is very good". Volkov stalemated the fight on top and forced the fight back to his feet, and Werdum was just out of gas.
Although Bangladesh edged past Sri Lanka in a nail-biter match, they could have done this in a better way. We look forward to a riveting end to the Nidahas Trophy which has been a brilliantly organised tournament.
Meanwhile, tight security arrangements were made by the Chandigarh police outside Burail jail in the wake of Tara's sentencing. Beant Singh was killed in a bomb blast outside the Punjab and Haryana Secretariat in August 1995.
When police broke into the vehicle, they found the family of four dead in the back of the auto near some clothes and groceries. It was believed the family had been in and out of the parking lot for the last month, Garden Grove Police Lt.
On January 20, Turkey launched a cross-border offensive into Syria, with the aim to dislodge Kurdish " terrorists " from Afrin. At least 200,000 civilians had fled the city over the last week, the Observatory said.
Powerball officials estimate that the winnings from the Saturday drawing total $456.7 million; $273.9 million cash value. Three other tickets sold in California, Missouri and Texas matched the first five numbers in the drawing.
Although the expressway is elaborately equipped with CCTV cameras and speed cameras, erring drivers are seldom brought to heel. Along with the three killed, four others were critically injured and taken to the nearby hospital.
Beast of the East II causes chaos on mid Wales roads
Heathrow, Gatwick, Stansted and Luton airports have advised passengers to check the latest flight information. Local media reported that most of the group were teenage girls, along with one adult in the safety vessel.
Russian Federation to expel 23 British diplomats
Britain and Russian Federation have each expelled 23 diplomats and taken other measures in the escalating tit-for-tat dispute. Chizhov was then asked if he thought Porton Down scientists were responsible for producing the nerve agent used in the attack.
Russia Retaliates Against UK
Johnson said the attack on Skripal and his daughter with a military-grade nerve toxin was most likely ordered by Putin himself. The BBC on Saturday said the police had made contact with Russians living in Britain to discuss their safety.