CCTV has been issued of a man police want to trace after a London Underground worker was “pushed” on to the tracks at Victoria station.
Transport for London (TfL) described what happened as “appalling and dangerous”.
The man was pushed while on a District Line platform at 10:00 BST on Tuesday 10 April.
Police said the member of staff did not suffer any injuries but was “understandably shaken”.
Insp Paula Jones, from British Transport Police (BTP), described what happened as “very serious” adding “urgent inquiries” were under way “to find the person responsible”.
“Thankfully, incidents such as this are very rare and I am grateful the victim was not injured,” she said.
A TfL spokesman added: “Everyone has the right to go about their day without fear or intimidation and we do not tolerate any form of physical or verbal assault on our staff or customers.”
Mick Cash, general secretary of the Rail Maritime Transport (RMT) Union, said safety reps were “pressing for all necessary resources” to be made to protect staff.
“Staff safety must never be left to luck,” he added.