British police are searching for two men after gas was released on a Tube train in central London.

A number of people were treated at the scene at Oxford Circus by paramedics for coughing and lack of breath.

British Transport Police there were no further concerns for their health and their symptoms "would suggest the gas is CS gas".

Officers have released CCTV images of two young men they want to trace after the incident, which was reported at 9.13am.