An area around the Cheesegrater has had to be cordoned off after two bolts fell from the structure with one landing on the ground.
Officially known as the Leadenhall Building at 122 Leadenhall Street, the skyscraper is to complete this year with tenants such as AON and Arup signed up to move in.
But an investigation has now been launched after the bolts fell from the 224-metre tall structure.
A statement from British Land, who are developing the Leadenhall Building with Oxford Properties, says:
A full investigation is being conducted by contractor Laing O’Rourke and structural engineers Arup. An examination is being undertaken of the remaining bolts. An area has been cordoned off around the base of the building while this process is ongoing. The Building Control Department has been notified.