British Transport Police sealed the area off the area to protect an alleged scene of crime area.
And later in the day, part of Breck Road was also closed off.
A British Transport Police spokesman said: "There has been an allegation of an assault on two women aged 21 and 24 who were coming to Poulton from Manchester.
"Details as yet remain unclear, but we will continue our investigations throughout the day."
He added:"One of the women is still being interviewed by officers and at this stage we cannot confirm the nature of the alleged assault or where it took place."
Detectives and crime scene investigators were continuing to conduct inquiries on the platform while the station is closed.
Train services were initially halted, with passengers having to find an alternative means of transport.
However, later in the day, trains were passing through the station, although not stopping.
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