The US National Science Foundation (NSF) said the telescope’s 900-ton instrument platform fell onto a reflector dish some 450ft (137m) below.
It came just weeks after officials announced that the telescope would be dismantled amid safety fears, following damage to its support system.
The Arecibo Observatory telescope was one of the largest in the world.
It was a key scientific resource for radio astronomers for 57 years, and was also made famous as the backdrop for a scene in the James Bond film GoldenEye and other Hollywood movies.
The NSF said there had been no reports of injuries following the collapse.
Read more – via the BBC: https://www.bbc.com/news/world-us-canada-55147973