Democratic New York state senator Chuck Schumer has claimed that the building - which was designed by an international collaboration that included the likes of Oscar Niemeyer and Le Corbusier - fails to meet almost all New York's building regulations.
He demanded that the UN prioritise a planned £1.6 billion renovation programme.
Schumer cited a statement by UN under-secretary Christopher Burnham last month in the US Congress, where he admitted that fire could 'engulf' the 1952 skyscraper in a matter of minutes.
'The building's grave state of disrepair may be hidden, but it is putting the health and safety of thousands who work within the building and in the area in a real degree of danger,' said Schumer.
'While the blue-green windows of the Secretariat building glisten on the outside, on the inside of the building, things are crumbling.
'These problems are not new,' Schumer added. 'The UN has known about them since the mid-'90s, yet to this day no work has begun and the money has not been allocated.'
The UN building was one of the first icons of post-war international Modernism, and one of the first additions to the Big Apple's skyline after the Second World War.
Schumer also warned that just a small amount of damage to one air-conditioning vent or pipe could see asbestos cover the building's interior.