A British couple may have been exposed to a deadly Soviet nerve agent through sheer bad luck.

Dawn Sturgess and Charlie Rowley are in a critical condition, after being exposed to Novichok near the site of the Skripal incident.

They appear to have been exposed to a contaminated object, while scrounging through a rubbish bin.

Investigative journalist Edward Lucas told Larry Williams it's unlikely anyone wanted them to be exposed.

"The most likely explanation for this, is that some quantity of Novichok leftover from the attack in March, wasn't picked up in the big clean up operation."

There will be some major questions asked of British authorities.

British police have previously insisted all public areas had been decontaminated and were completely safe.

LISTEN TO EDWARD LUCAS TALK WITH LARRY WILLIAMS ABOVE