THE chemical attack in Salisbury was a “brazen and reckless act" and the UK Government stands ready to act as a clearer picture emerged, Amber Rudd has told MPs.

In an emergency Commons statement, the Home Secretary refused to say whether or not she regarded Russia as responsible, saying the investigation should be based on "facts, not rumour".

She told the House: "The use of a nerve agent on UK soil is a brazen and reckless act. This was attempted murder in the most cruel and public way. People are right to want to know who to hold to account.

"We are committed to doing all we can to bring the perpetrators to justice; whoever they are and wherever they may be," declared Ms Rudd.

Responding to a suggestion from Sir Edward Leigh, a Conservative former minister, that if Russia were responsible, then it amounted to an "act of war", she said: "There will come a time for attribution and there will be, then, consequences and there will be further information that follows."

The Secretary of State, who named the victims publicly for the first time, said Sergei Skripal, 66, and his 33-year-old daughter Yulia "remain unconscious and in a critical but stable condition".

The unnamed police officer who rushed to their aid is out of intensive care and is talking in his hospital bed but he remains in a serious condition.

Ms Rudd described the nerve agent used in the attempted double murder as “very rare”.

Counter-terror police are working around the clock to unravel what is now feared to be a sophisticated chemical weapon plot amid heightened tensions between Britain and the Kremlin.

Earlier today, Gavin Williamson, the Defence Secretary, said Russia was becoming an "ever-greater threat" while a senior general warned that Moscow was "capable of anything".

Mr Williamson told ITV1's Good Morning Britain that the Kremlin had become more aggressive, including in the north Atlantic, adding: "Russia's being assertive, Russia's being more aggressive, and we have to change the way that we deal with it because we can't be in a situation in these areas of conflict where we are being pushed around by another nation."

Meanwhile, General Sir Chris Deverell, who oversees military intelligence as head of the Joint Forces Command, said in a speech at the Defence Academy in Shrivenham, Oxfordshire, on Wednesday that Russia could seek to control systems such as traffic signals and the power grid.

He said: "They care only about what is in the interests of their elites. They don't care about innocent people going about their lives. They are quite honestly capable of anything."

Sir Andrew Wood, the former British ambassador to Russia, told the Daily Telegraph that the "assassination attempt" was more serious given a police officer was among the injured.

Assistant Commissioner Mark Rowley, the head of counter-terrorism policing, has revealed that Sunday's incident in Salisbury, Wiltshire, was being treated as attempted murder and the pair had been "targeted specifically".

He declined to specify the nerve agent or how it was administered, stressing: "Our role now of course is to establish who is behind this and why they carried out this act."

Police have appealed for anyone who was in Salisbury city centre on Sunday to come forward to help with the "missing pieces" in the case.

Hundreds of detectives, forensic officers and analysts are working on the case, which has drawn comparisons to the poisoning of former Russian intelligence officer Alexander Litvinenko on British soil in 2006.

Nerve agents, which are chemical weapons, have been used in assassinations and attacks in war zones in recent years.

Kim Jong Un's half-brother Kim Jong Nam was killed at an international airport in Malaysia last year in an attack using a nerve agent known as VX.

Another well-known nerve agent, sarin gas, killed more than 90 people in a rebel-held area in Khan Sheikhoun, Syria, drawing international condemnation of the Bashar Assad regime.

Access to such toxins are tightly regulated, meaning the Salisbury incident would have taken considerable planning to execute.

Russia has denied responsibility for the attack, which comes seven years after Mr Skripal was released from the country as part of a spy swap with the US.

He had been convicted in his home country in 2006 for passing state secrets to MI6.