London, July 5: A man and woman found unconscious in Wiltshire, England, were poisoned by Novichok -- the same nerve agent that poisoned ex-Russian spy Sergei Skripal, police said.

The couple, believed to be Charlie Rowley and Dawn Sturgess, are in a critical condition having been found unconscious at a house on Saturday, the BBC reported.

Police said no one else has presented with the same symptoms. There was "nothing in their background" to suggest the pair were targeted, the Metropolitan Police said.

Government will hold an emergency Cobra meeting on the probe on Thursday.

The Counter Terrorism Policing Network is now leading the investigation, working with Wiltshire Police.

Assistant Commissioner Neil Basu said it could not be confirmed whether the nerve agent came from the same batch that Skripal, and his daughter Yulia, were exposed to.

But he said the possibility was "clearly a line of enquiry".

Basu said no contaminated items had yet been found, but officers were putting together a "very detailed examination of (the couple's) movements" in order to determine where they were poisoned, the BBC reported.

He added that members of the public should not pick anything up if they do not know what it is. "We have no idea what may have contained the nerve agent at this time," he said.

Home Secretary Sajid Javid said the events follow "the reckless and barbaric attack which took place in March". But added that Public Health England has made clear, the risk to the general public is low.

On Saturday, paramedics were called twice to the property in Amesbury - in the morning, after Sturgess had collapsed, then later the same day, after Rowley had also fallen unwell.

The news that Novichok was to blame was confirmed following analysis at the defence research facility at Porton Down, Wiltshire.

UK couple were poisoned with nerve agent: Police