Russia mounted a cyber attack on the global chemical weapons watchdog while it was investigating the Salisbury spy poisoning, the British and Dutch security services have revealed.

Authorities in the Netherlands named four GRU operatives who travelled to Amsterdam and attempted to hack into the Organisation for the Prohibition of Chemical Weapons (OPCW) network directly.

The four men - named as Alexei Moronets, Evgeni Serebriakov, Oleg Sotnikov and Alexei Minin - flew from Moscow to Amsterdam on April 10 on official passports, where they were met by a Russian embassy official.

Three days later, they parked in a rental car outside a hotel near the OPCW building, with specialist technical equipment in the back of the vehicle designed to hack into the watchdog’s network.

The attempt on the OPCW headquarters followed unsuccessful "spearfishing" attacks by the GRU on the Foreign Office and on the defence laboratories at Porton Down, which was also investigating the Salisbury attack.

Foreign Secretary Jeremy Hunt said Russia could face further sanctions in the wake of the dossier of "hard evidence" revealed on Thursday.