Today's fire comes after another blaze broke out beside the tracks in late April.
A statement from the NYMR read: "We can confirm that there has been a lineside fire at the North Yorkshire Moors Railway, which broke out today at around 12pm on the stretch of line between Goathland and Levisham stations. The fire was identified by NYMR’s fire patrol team, who escalated the response to the emergency services, North York Moors National Park and local gamekeepers.
"Passengers should still arrive for their set departure times, where further updates will be provided by station staff. We are expecting some delay in transporting passengers via road. The heritage railway is doing everything it can to fully cooperate with the emergency services, taking every precaution to ensure the safety of both staff and passengers, which is always our priority.
“Due to tinder dry conditions, which is unusual for this time of year, we have made the decision to reduce the amount of steam hauled services, whilst we are still experiencing a long spell of dry weather. Changes to the timetable will take place this week and will affect the internal services (Moors Explorer services) which will be operated with either a heritage diesel locomotive or scenic diesel railcar”.
Lineside fires are ignited by embers from steam engines passing, and the issue has also affected the Embsay and Bolton Abbey Railway in recent weeks. On Mother's Day in March, three fires broke out on the same day and trains had to stop running.