Scotrail announced that the fire was the cause of disruption, not a signalling fault as initially reported.
Trains between Edinburgh and Milngavie via Airdrie have been suspended with alternative travel being offered by operator, ScotRail.
Services have been disrupted due to a lineside fire, near Blackridge, which has caused damage to signalling infrastructure in the area.
The fire appears to have started outwith the railway boundary, but subsequently spread onto our infrastructure. The incident is being investigated by the BTP and fire service as potentially malicious.
The blaze was first reported at around 21:30 last night, and the line was closed and OLE power supply cut to allow the fire service to tackle the incident.
Although the fire was extinguished by midnight repairs began at around 02:00 after specialist officers had completed their on-site investigations.
Engineers have been working since then to repair / replace the fire damaged assets and also to bring signals back on line. Those repairs are ongoing.
A ScotRail Alliance spokesman said: “As a result of this incident last night, trains have been suspended between Airdrie and Bathgate.
“To keep people moving, replacement shuttle buses are running between Airdrie and Bathgate and valid train tickets can be used on Lothian Buses and Edinburgh Trams between Edinburgh Park and Edinburgh.
“Customers are also reminded to retain their tickets in order to reclaim through our Delay Repay scheme if their journey is delayed by more than 30 minutes.”
Queen St - Edinburgh via Falkirk High and Edinburgh via Shotts services aren’t affected.
Detectives from British Transport Police are currently investigating the incident which caused significant damage to the railway close to Blackridge station, Scotland.
Investigating officer DC Niall McGugan, said: “Although this fire was contained very quickly, the damage was extensive and the repair cost will be significant. Whilst we are still working to determine exactly what happened, at this time we are working to the presumption that this fire was started deliberately.
“I am very keen to speak with anyone who may have been in the area at this time or saw anyone acting suspiciously. Please get in touch as your information may help us investigate.”
Anyone with any information can contact BTP by sending a text to 61016 or by calling 0800 40 50 40 quoting reference 560 of 18/01/2017. Alternatively, they can pass information anonymously to independent charity Crimestoppers on 0800 555 111.