Russia has explored carrying out assassinations by placing nerve agent Novichok on door handles, the Daily Mail can reveal.

Police have already disclosed they believe Sergei Skripal and his daughter were poisoned in Salisbury after the poison was smeared on the double agent’s front door.

Now British intelligence agencies have evidence that Russia had been testing the deadly agent specifically on door handles in the run-up to the attack on March 3.

Agents also have highly sensitive information showing Moscow tested the poison on other ‘everyday objects’, it emerged last night.

A security source said: ‘We have intelligence that goes beyond Russia made Novichok and stockpiled it. 

'We have evidence that they also explored using it as an assassination weapon including on areas such as door handles and everyday objects.’

The detail was one of several crucial pieces of evidence that led the UK government to determine that it was ‘highly likely’ that Vladimir Putin’s regime was behind the attack.

Sources also revealed last night that foreign intelligence agencies have been passing top-secret information to the UK that pointed the finger at the Kremlin.

While it is not known what intelligence has been given to British agencies, or which countries supplied it, the information was said to have added further weight to the UK’s dossier on the attack.

Sources said all the evidence amassed by intelligence agencies, the military, and the Government laid the blame firmly at Russia’s door.

They would not say when the evidence of Russia testing Novichok on door handles had come to light for security reasons – confirming only that the details had been unearthed in ‘recent times’.

A source said this key evidence had been handed over to Britain’s allies in a move described as unprecedented intelligence sharing.

Read more on dailymail.co.uk.