A FORMER Russian spy and his daughter were deliberately targeted with a nerve agent in an attempted murder, police have said.

Investigators have revealed Sergei and Yulia Skripal were poisoned before they collapsed on a park bench at the Maltings, in Salisbury, on Sunday.  

Met Police chief Mark Rowley disclosed that the pair were "targeted specifically" however he could not state which nerve agent was used.

Mr Rowley added: "This is being treated as a major incident involving attempted murder by administration of a nerve agent.

"As you know these two people remain critically ill in hospital.

"Sadly in addition a police officer who was one of the first to attend the scene and respond to the incident is now in a serious condition in hospital." 

Wiltshire Police are said to be providing support to his family.

Dame Sally Davies, chief medical officer, added that the incident possesses a low risk to the public.

"Of course, public safety remains a priority and this is clearly and awful incident and I know that local people will be concerned but I would stress that at the moment we are not seeing any evidence of a wide spread health risk," Mr Rowley said. 

"Having established that the nerve agent is the cause of the symptoms leading us to treat this as attempted murder. I can also confirm that the two people who originally became unwell were targeted specifically.

"Our role now is to established who is behind this, to that end we have hundreds of officers, forensic specialists, analysts and intelligence officers working together around the clock to on this case.

"For example we are reviewing hundreds of hours of CCTV and building a detailed timeline of events.

"Specialist officers in protective clothing will continue to be visible in the centre of Salisbury as they go about their work. It is a sensible procuration that I hope will not alarm the community.

"We do have well practiced procedures to deal with chemical incidents." 

Mr Rowley said they needed to be “painstaking and thorough” to secure the maximum amount of evidence,” adding: “Indeed the work in Salisbury may take several days. “

He thanked those who have already helped with the investigation and is looking for anyone with images or footage to supply it.

"We will continue to work with a range of agencies in Wiltshire to progress this investigation as fast as we possibly can."

Mr Rowley would not disclose any more information on the nerve agent, but the most common types are VX and Sarin.

Sarin is a liquid that is clear, colourless, tasteless and odourless.

VX is one of the deadliest chemical weapons ever created, and just 10 milligrams is enough to kill.