A 33-year-old woman has been arrested over a major blaze which closed Nottingham railway station last month.
British Transport Police said the suspect was detained in Derby on suspicion of arson and is in custody.
The fire on Friday January 12 is believed to have started in a toilet block and caused major disruption to rail passengers.
British Transport Police said: "Inquiries are ongoing and officers are continuing to appeal for information."
Detective Inspector Granville Sellers said officers would particularly like to speak to anyone who was at the station between 5am and 6.30am on January 12, who may have seen something or somebody which caught their attention.
"It may have seemed insignificant at the time but it could prove vital to the investigation."