A man has been arrested on suspicion of assaulting former health secretary Matt Hancock in a Tube station, British Transport Police have said.
The force received a report of a man "being assaulted and harassed" at Westminster station at 8.47am on Tuesday.
"A 61-year-old man has been arrested on suspicion of common assault and a public order offence and remains in custody," it said.
"Enquiries into the incident are ongoing."
It is understood the MP for West Suffolk, who recently came third in the most recent series of I'm A Celebrity...Get Me Out Of Here!, was unhurt in the incident.
Mr Hancock is understood to have been in the station when the incident started, before it continued on a train.
A spokesman for Mr Hancock said it was a "very aggressive and unpleasant encounter with a dangerous conspiracy theorist".
"Both Transport for London staff and the British Transport Police were fantastic and the man has since been arrested," he added.
"Fortunately, this sort of behaviour is a rare occurrence, but it's instances like this that reemphasise the importance of shutting down baseless misinformation which causes so much harm.
"Matt wants to put on record his thanks to TFL and the British Transport Police for their extraordinary work."