A man has been arrested by armed police after an incident in Whitehall, near Parliament.
A witness described seeing two knives on the ground, one of which he described as a large bread knife.
A Metropolitan Police statement said there were no injuries in the incident close to the junction of Parliament Street and Westminster Bridge Road.
Security remains tight outside Whitehall buildings following the terror attack on 22 March.
Khalid Masood killed four people when he drove along Westminster Bridge on that day. He then got out of the car and stabbed PC Keith Palmer to death at the entrance to Parliament.