Yulia Skripal, who was poisoned along with her former double agent father Sergei in Salisbury last month, has been discharged from hospital.
The 33-year-old Russian national had spent more than a month in hospital after coming into contact with the military-grade nerve agent Novichok.
She is reported to have been released on Monday and taken to a secure location.
The pair were left fighting for their lives after being found unconscious on a park bench in the Wiltshire town on March 4.
On Friday, doctors at Salisbury District Hospital said Mr Skripal, 66, was “responding well to treatment, improving rapidly and no longer in a critical condition”.
But the Foreign Office has said the pair are likely go have “ongoing medical needs”.
Moscow has denied being responsible for the poisoning of the Skripals but the incident has plunged diplomatic relations between Russia and the West into the deep freeze.
Foreign Secretary Boris Johnson used a Sunday Times article to accuse Labour leader Jeremy Corbyn of lending “false credibility” to Moscow by not blaming the Russian state unequivocally over the incident.
Mr Johnson said the Kremlin had released a “torrent of absurdity” following the attack.