Passengers using the Tyne and Wear Metro must continue to wear face coverings when travelling on the system, unless they are exempt.
Nexus said that wearing a face covering throughout journeys, on stations and trains, is a condition of carriage unless exempt. Passengers may be refused travel if they do not.
North East Council leaders have asked for legal powers to enforce wearing face coverings on public transport. The government has said people should continue to wear masks in crowded places, despite relaxing restrictions from July 19.
Huw Lewis, Customer Services Director at Nexus, said: “We are all expected and recommended to keep wearing face coverings in busy indoor settings, including shops and on public transport.
“We will be encouraging customers to follow this advice when making journeys and we will have extra teams out on Monday to talk with customers about why that’s the right thing to do for everyone.
“We have made wearing face coverings part of Metro’s conditions of carriage, unless you are exempt, and we will use that as a base to encourage people to do so in busy spaces. It has never been a legal requirement to wash hands regularly, but we’ve all been doing that and we should take the same approach to face coverings.
“Encouraging people to do the right thing is as important as enforcement powers in keeping everyone safe, and we are joining the much larger North East England campaign with health chiefs, local councils and businesses to promote positive behaviour.
“We want there to be a single clear message about what customers should do on public transport, whether it be Metro or bus or Ferry in North East England. Local authority leaders have contacted the Government to ask for clear and consistent powers across the industry which we will support if they are brought in.”