Enforcement action has been taken against a quarter of sites blitzed by the Health and Safety Executive in south London.
The initiative, part of a rolling inspection campaign, saw the regulator visit 40 sites in Wandsworth, Lambeth, Greenwich, Croydon, Bromley and Southwark in March.
Of the sites visited, a quarter revealed problems, including unsafe work at height, which led to enforcement action being taken at 10 of them.
HSE principal inspector for construction in south London Andrew Beal said: “Many of the sites in south London had unacceptable safety standards.
“At a residential block in Stockwell, for example, inspectors served prohibition notices on the site operator, who was putting workers at serious risk of fatal falls from the building.”
The HSE revealed it had served four enforcement notices across nine sites in Lambeth, two from three sites in Greenwich and four across the 16 sites it inspected in Wandsworth.
The HSE inspected more than 1,500 refurbishment sites across Britain last month as part of its Shattered Lives campaign tackling poor safety standards.