Police were called at 11:29hrs on Wednesday, 29 March to Westminster Bridge, SW1 to reports of a man in the River Thames.
Emergency services attended to try and locate the man, who was reported to be aged in his 20s.
Despite an extensive search, services were unable to locate the man.
The search has now been stood down.
This is not being treated as suspicious.
At 13:11hrs the same day, a woman was reported to have fallen from the south east corner of Westminster Bridge into the River Thames.
Emergency services attended and a woman was recovered safe from the water.
She is being treated by London Ambulance Service and will be dealt with under the Mental Health Act.