Do you recognise this man? (Credit: British Transport Police)
The victim was travelling on a Tube between Whitechapel and West Ham stations when the suspect stood on her foot.
They both got off at West Ham and boarded a second train travelling towards Barking.
As the man was about to disembark the train at Barking, he lowered his face covering and spat at the victim.
The incident happened shortly after 6.30pm on Friday, 11 June.
Officers have released a CCTV image of a man who may have information which could help their investigation.
If you recognise him, or have any information, please contact BTP by texting 61016 or calling 0800 40 50 40 quoting reference 570 of 11/06/21.
Alternatively, you can call Crimestoppers on 0800 555 111.
For more on this story, and the latest on our other local and national news, listen to Time 107.5FMTags: Newham, West Ham, Barking, Barking and Dagenham, British Transport Police
© TIME107.5fm 2015-2021. All rights reserved.