Translink has announced cross-border timetable changes in response to the latest coronavirus restrictions.
Early morning and late evening services between Belfast and Dublin will be suspended from Monday. Services will also be operated by non-Enterprise trains.
Translink said it was adopting a cut in services based on restrictions on non-essential travel.
A spokeswoman added: "Translink would remind those making essential journeys to wear a face covering, practice good hand hygiene, socially distance and use contactless payments to minimise interaction, so together, we can keep everyone safe and limit the spread of the virus.
"We continue to use enhanced cleaning regimes using the latest cleaning technology and long-lasting anti-viral disinfectant that kills viruses and bacteria on contact providing ongoing protection and means our fleet and facilities are cleaner than ever.
"We would encourage our customers to familiarise themselves with any changes to their specific services in case they need to adapt their travel plans.
"Full details of the new timetables are available on Translink’s website and journey planner www.translink.co.uk Passengers are also advised to buy their tickets in advance through the website."
The move comes after the public transport provider slashed Northern Ireland bus and rail services in response to the Executive's stay-at-home order in a bid to stem the spread of the virus.
First Minister Arlene Foster has said the lockdown restrictions are having an effect, as the transmission rate of the virus had dropped below one - meaning spread was on the decrease.
Coronavirus pressures on Translink has resulted in a £100million shortfall in its finances. Passenger numbers have been severely reduced through the lockdowns and advice for people to work from home if they can.
The Executive agreed to provide £30m to help Translink continue. Prior to the pandemic, warnings had been issued around low cash levels at Translink and the situation was getting close to a crisis point.
Infrastructure Minister Nichola Mallon has said reduction in transport services will allow Translink to focus on providing travel for key workers and ensure people have access to essential services. She has urged people to consider if their journey is essential.
"I can assure the public that no geographical area is losing services and people will continue to be able to practise social distancing on our public transport network," she said.
Services suspended from Monday, January 8: