Train users urged to wear face masks on inter-city services
And customers are being warned they may be prevented from boarding inter-city trains without a reservation as part of social distancing measures.
This means passengers who have bought a ticket without a reservation may not be allowed to travel on the next train that arrives.
The measures have been announced ahead of timetables being increased on Monday and following updated travel advice by the Government.
Phil Whittingham, managing director of Avanti West Coast, 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.
Services across the network will be ramped up from around 50 per cent of the normal timetable to 70 per cent from 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 an increase 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 per cent of the normal number of people who travel.
Those who have no alternative means of making their journey are asked to avoid peak times.
RDG director of nations and regions Robert Nisbet said: "To keep people safe, there will only be space on trains for as few as a tenth of the usual number of people despite train companies gradually increasing services next week.
"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.
"We are doing everything possible to keep passengers and staff safe, including cleaning trains and stations several times a day, managing capacity and increasing signage to help people get around.
"For those who do need to take the train, we ask that they plan ahead, consider others and stay safe when they use public transport.
"That means buying tickets online for quieter times of day, maintaining social distancing wherever possible, wearing a face covering and keeping hands sanitised."