Security services located the source of the nerve agent used to poison Russian spy Sergei Skripal and his daughter Yulia, it has been claimed. 

According to reports, officials found the Russian laboratory where the novichik poison was made in the days after the attack on March 4. 

This comes after the chief of the Ministry of Defence's Porton Down laboratory said it had 'not verified the precise source' of the Novichok nerve agent - prompting a furious backlash from Russia.

The admission was seized upon by President Vladimir Putin who demanded an apology from Britain and called for a full inquiry after it summoned an emergency meeting of weapons inspectors at the Hague. 

Despite the blunders, the EU yesterday insisted it retained 'full confidence' in the UK's investigation of the Salisbury nerve agent attack and said Russia was to blame.

Brussels issued a strong statement in support of Britain as ministers scrambled to shore up the international coalition standing against the Kremlin.  

Britain branded the plea for an apology from Russia 'perverse' and ministers hit out at the Russian claims.

Foreign Secretary Boris Johnson was under fire yesterday after he previously claimed Porton Down scientists had given him 'absolutely categorical' evidence the Novichok used to poison Sergei Skripal had come from Russia.

Putin has denied responsibility and demanded access to the British investigation into the March 4 attack on former spy Sergei Skripal and his daughter Yulia.