Trump Tower: Human fly attempts to scale Donald Trump's New York landmark

The 20-year-old climber was detained by police after making it as far as the 21st floor

A suspected Donald Trump supporter who tried to climb Trump Tower on Manhattan's Fifth Avenue was yanked inside by police after making his way as far as the 21st floor using a suction cup contraption.

To the annoyance of emergency services and the glee of onlookers, the man began scaling the smooth glass surface of the 58-storey tower at the heart of the Republican presidential nominee's property portfolio on Wednesday afternoon.

Police and firefighters struggled for around two hours to reach him and curtail the stunt, after the daredevil began his climb from a public roof garden on one of the skyscraper's lower levels. A crowd gathered to cheer him on from the ground.

An NYPD spokesman told ABC News that officers were trying to "safely isolate" the climber to prevent him getting any higher. "The guy doesn't appear to be here to do anything evil," the spokesman added. After he was detained at about 6.30pm, the 20-year-old man told police his name was Steve and that he was from Virginia, CNN reported.

In a video uploaded to YouTube on Tuesday and entitled "Message to Mr Trump (why I climbed your tower)", a man bearing a strong resemblance to the climber said he was an "independent researcher seeking a private audience" with the alleged billionaire "to discuss an important matter".

Suggesting he was a Trump supporter, the man urged anyone else watching the clip to "be sure to get out and vote for Mr Trump in the 2016 election."

Michael Cohen, an executive with the Trump Organisation, described the stunt as “ridiculous and dangerous,” Michael Cohen, saying in a statement" “I'm 100 percent certain the NYPD had better things to do.”