A man has been arrested after police were called to investigate a Victoria Line train after reports of a “noxious substance” on board.
Member of the public reported a man harassing people who was believed to be carrying a container of petrol.
The British Transport Police officers halted the trains to search for the suspected substance and arrested a man later as Waterloo.
Passengers reported seeing police officers searching the platform and walking through the train “looking for someone in dark clothing”.
@victorialine why are the police investigating our tube? 😲— Harriet Carter (@HarrietLCarter) April 28, 2017
One person tweeted that she police were walking up and down the train asking if passengers had seen someone in a gas mask.
The train service was halted as police invested but resumed shortly after, with BTP tweeting that it was declared "non-suspicious".
A BTP spokeswoman said: "A man has tonight been arrested on suspicion of carrying a noxious substance on the railway and a public order offence in connection with incidents on the Victoria Line.
"We were called at 5.25pm to Highbury and Islington underground station after a member of the public reported a man carrying a container of what was believed to be petrol. He was harassing members of the public, causing some alarm, and continued this behaviour at a number of stations on the Victoria Line.
"Officers attended and carried out a full search of the station and the Victoria Line.
"A 28-year-old man from London was arrested shortly after 7.30pm at Waterloo station and is currently in custody.
@victorialine Was only minor delays, then guy at the gate at vauxhall turns people away saying there's a security incident at Victoria. 😠😠😠— Nix C (@perpglo) April 28, 2017
"We would like to thank the public for their patience this evening."
There are severe delays on the rest of the line as a result of the earlier closure. Photos on Twitter show hoards of people queuing to get into stations.
The delays come as hundreds of Londoners attempt to travel out of the capital for Bank Holiday breaks.