Police on Wednesday captured a climber scaling Trump Tower, dragging him to safety through an open window on the 21st floor of the New York headquarters of the Republican nominee for US president.

Live television footage showed uniformed officers reaching out and grabbing the young man -- dressed in grey shorts, an olive T-shirt and white cap -- around three hours after he started his ascent using five suction cups.

"The climber has been taken into custody," a police spokesman tweeted.