Soldiers and military equipment arrived in Salisbury on Friday afternoon to assist police in their investigation of the nerve agent attack on former double agent Sergei Skripal.
Large army vehicles and people in protective suits could be seen at Salisbury Hospital just after 5pm local time.
The new deployment came as British ministers announced 180 troops have been deployed to the area to assist police with the probe.
Sergei Skripal and his 33-year-old daughter are in critical condition in Salisbury District Hospital after being found unconscious on a park bench last Sunday. Police confirmed they are treating the matter as attempted murder by a nerve agent.