A train operator is to ban passengers from travelling without a reservation to allow it to enforce social distancing.
London North Eastern Railway (LNER), which operates journeys to the UK capital from Scotland on the East Coast Main Line, will introduce the measure when services are ramped up next week.
A spokesman said: “The safety of our staff and customers is always our top priority.
“To support social distancing for customers who do need to travel with us at this time, all LNER services will be reservation-only from Monday.”
It is asking passengers to ignore their reserved seat and to sit in a window seat, with one person per row of four seats, and two empty rows between each passenger.
People travelling as a household will be allowed to sit together but must maintain “a safe distance” from other passengers.
Avanti West Coast, which operates intercity journeys on the West Coast Main Line, including to and from Scotland, warned its customers that anyone without a reservation may not be able to travel on their choice of train due to capacities being limited to around a quarter of normal levels.
Managing director Phil Whittingham said: “We’re appealing to our valued customers to help us and other passengers by only travelling with a reservation.
“If everyone does this, we’ll be able to keep social distancing in place on board, both for our customers and our people.
“If customers do turn up without a reservation, we’ll do our best to help but we can’t guarantee they’ll be able to take the train they want.”
The firm has introduced a series of additional hygiene measures, including issuing staff with face masks, enhanced cleaning regimes and closing waiting rooms and lounges.
Transport operators are being urged by the Government to rearrange, remove or limit seating “to try and ensure social distancing is observed”.
This may include blocking off seats in close proximity to others and removing face-to-face seating.
Passengers are asked to keep a two-metre distance from other people where possible and to wear a face covering.
Services across the rail network will be increased from around 50% of the normal timetable to 70% on Monday, as part of the easing of coronavirus lockdown restrictions.
Industry body the Rail Delivery Group (RDG) is urging passengers to avoid non-essential travel after recording a rise in journey planning of nearly a quarter this week.
It said 3.7 million journeys were planned between Sunday and Thursday, compared with three million over the same period one week earlier.
Passengers are being asked to drive, cycle or walk to their destinations instead of using public transport.
The RDG warned that the capacity of trains will be restricted to as little as 10% of the normal number of people who travel.
RDG director of nations and regions Robert Nisbet said: “We need people’s help to keep trains clear for those who really need them, so we are asking people to consider alternatives like cycling or walking, and if that’s not possible, to travel at quieter times.”