A pharmaceutical executive standing behind US President Donald Trump collapsed in the White House during an announcement about weight-loss medication.

The man's legs appeared to suddenly buckle as officials around him attempted to steady his fall and prevent him from hitting his head.

Footage from the drama in the Oval Office on Thursday (Friday AEDT) showed Trump standing from his desk and looking at the man as a White House medical rushed to his aide.

He was later identified as Gordon Finlay, a senior executive with Swiss-based pharmaceutical giant Novo Nordisk.

White House officials quicky ushered reporters and camera crews from the Oval Office.

Press Secretary Karoline Leavitt said in a statement: "During the Most Favored Nations Oval Office Announcement, a representative with on

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