Passengers were left coughing and in need of medical assistance after the two men left off the gas at Oxford Circus at 9.13am on Saturday.
British Transport Police have released images of the pair they are looking for.
Several people were treated on the platform by paramedics.
A police statement read: “BTP officers are today releasing CCTV images after a gas was released on board a train carriage at Oxford Circus station.
“The incident was reported at 9.13am on Saturday 20 July.
“A number of people were treated at the scene by paramedics for coughing and lack of breath. There are no further concerns for their health.
“Their symptoms would suggest the gas is CS gas.
“Officers believe the people in the images may have information that could help their investigation.
Source: Read Full Article