And the BTP officers have identified a male train passenger who was at the station around the time of the incident and who could hold key information about the incident.
Investigators are hoping to speak to the man as soon as possible.
They are still appealing for witnesses following the complaint early on Tuesday morning.
The assault claims involved a 21-year-old from Poulton who had travelled on the 11.11pm train on Monday night from Manchester Piccadilly to Blackpool North.
She later alighted at Poulton around 12.30am and was found in a dishevelled state in the town centre by an off-duty police officer shortly after.
"We have spoken with witnesses and reviewed CCTV," said Detective Inspector Andrea Rainey, the investigating officer, "but we are also asking for help from any members of the public, especially anyone who may have been on the train to Blackpool North or who was at Poulton le Fylde station in the early hours of Tuesday morning.
"We are asking anyone who may have witnessed the assault or who may have information that can assist our investigation to contact us."
A 24 year old woman who was thought to have been a second assault victim is being treated as a witness by police.
Officers from British Transport Police and Lancashire Police attended the station early Tuesday morning and it was then closed off for forensic examination, which also extended to an area of Breck Road outside.
"I am treating this incident very seriously," added DI Rainey, "and ask anyone with any information about this assault to come forward and talk to us."
Anyone who has any information about the incident is asked to contact BTP on Freephone 0800 40 50 40 quoting incident 50 of 24/06/08 or call Crimestoppers anonymously on 0800 555 111.