Police cordons are to be lifted at all sites in Salisbury to allow decontamination to start, apart from at the home of Sergei Skripal.
More than two months after the former spy and his daughter Yulia were poisoned with a nerve agent, all but one site in the Wiltshire city has now been released by police.
Officers are continuing to trawl through more than 5,000 hours of CCTV and examine more than 1,350 exhibits as they continue their investigation into the use of a chemical weapon on 4 March, which has been blamed on Russia.
The Cabinet was given an update at a meeting on Tuesday, in which ministers were said to have “praised the resilience of the residents of Salisbury in the face of widespread disruption caused by Russia’s reckless actions”.
Describing Salisbury as “safe” and “open for business”, the Prime Minister’s official spokesman said: “The police have now released all the sites for decontamination, except for the Skripal house.
“Clean-up work is well under way and the priority is making the sites safe so they can be returned to use and Salisbury can get back to normal.
“The ongoing investigation is one of the largest and most complex ever undertaken by counter-terrorism policing.
“Over 250 officers from across the counter-terrorism policing network have been deployed, alongside over 160 officers from Wiltshire Police and a range of experts and partners.
“Officers continue to trawl through over 5,000 hours of CCTV and examine over 1,350 exhibits that have been seized.
“Around 500 witnesses have been identified and hundreds of statements have been taken.”
Last week, Ahmet Uzumcu, head of the Organisation for the Prohibition of Chemical Weapons, revealed the Skripals were poisoned with up to 100 milligrams of novichok.
He said the amount used suggests it was created for use as a weapon rather than for research purposes and could have been applied as a liquid or aerosol.
Despite initial fears for their lives, Ms Skripal has been discharged from hospital and her father is no longer in a critical condition.