Witnesses have described their horror at seeing a man plunge to his death at the Tate Modern.

The man, in his late 40s, fell 100ft from a balcony at the Members' Room onto the pavement below. He was declared dead at the scene.

Members of the public had been enjoying an evening on the sun-soaked riverbank of the Thames when the "well-dressed" man hurtled to the ground.

Twitter user @CathHannahx wrote on the site: "Seeing the guy who jumped off the Tate Modern has been the most traumatic thing I have seen."

She added that she had "no idea" why he had done so.

Another user, @salmasaid, wrote that many believed the death to be a stunt, adding: "The shock made everyone, including us, think that this was not real and that this was some outrageous performance. It's really sad."

Members pay upwards of £60 a year and have access to the exclusive bar, which is being refurbished next year, and free tickets to all exhibitions at the gallery.

A Scotland Yard spokeswoman said: "Next of kin are aware. A post-mortem will be held in due course. An inquest will open and be adjourned in due course. The death is being treated as non-suspicious."

She added that it would be for the coroner to determine whether or not the man had killed himself.