A man suffered a broken nose and lost a tooth in a fight with two other men on a train from London to Essex.
British Transport Police (BTP) on Friday released CCTV images of two men they want to speak to in connection with the incident.
Around 10.30pm on October 24, two men on a Greater Anglia train from London Liverpool Street to Braintree "became involved in a fight with another man", said BTP in a statement.
"One man received a broken nose and lost a tooth.
"Officers believe the men in the images may have information which could help their investigation.
"If you recognise them, witnessed anything, or if it happened to you, please contact us and our officers will be able to help."
Anyone with information is asked to contact BTP by calling 0800 40 50 40 or texting 61016, quoting reference 207 of 28 October 2023.