cheesegrater or Leadenhall
The Leadenhall Building has been dubbed the Cheesegrater for its distinctive shapeGetty

Two steel bolts the size of a human arm have broken off one of London's tallest skyscrapers and plummeted to the ground before horrified pedestrians.

The bolts came off British Land's 737ft Cheesegrater skyscraper in the City of London, which has now been cordoned off from the public.

A person close to the company told The Telegraph the broken bolts could have caused "significant damage" had they hit and injured anyone walking below.

British Land revealed the damage at a stock exchange announcement, but the real estate group said no one was injured in the incident and "there is no risk to the structural integrity of the building", which has the address 122 Leadenhall Street.

It is understood that one bolt fell from the fifth floor earlier in the week, while the second broke off the fifteenth floor on Wednesday – falling into an area that was already cordoned off for construction.

The pavement surrounding the skyscraper, which is the fourth tallest building in the capital, has been cordoned off while safety checks take place.

British Land became the principle tenant of the tower in 2011, after signing an agreement with insurance giant Aon. Last month the newly-completed building smashed the City's rental records by agreeing a deal with American insurance group FM Global to take the 41st floor of the tower at £85 per sq ft.

The Cheesegrater's wedge-shaped angle was necessary to preserve the view of St Paul's Cathedral, according to the St Paul's Heights policy, devised in 1934.