The firm is telling customers to stop sending items abroad while it tries to resolve the issue.
Image source, Getty ImagesRoyal Mail says it is unable to send letters and parcels overseas after a “cyber incident”.
It is telling customers to stop sending items overseas while it tries to resolve the issue.
The firm said there were also minor delays to deliveries into the UK, but domestic deliveries are unaffected.
It apologised and said its teams were “working around the clock to resolve this disruption” and would update customers when it had more information.
Royal Mail is understood to be calling it a “cyber incident” rather than an attack because it does not know what has caused the issue.
It said its computerised systems for sending letters and parcels abroad had been “severely disrupted”.
A spokesperson said: “We immediately launched an investigation into the [cyber] incident and we are working with external experts.”
It is understood that the National Cyber Security Centre, which is part of the UK’s cyber intelligence agency GCHQ, is involved in trying to work out what has happened.
Regulators have also been told of the incident.
In the year to March, Royal Mail sent 152 million parcels abroad which equates to around 200,000 items a day.
However, that was a small fraction of the number of parcels it sent domestically.
Royal Mail has faced a number of challenges over the past year, including a series of strikes by postal workers as part of a long-running dispute over pay and conditions.
The Communication Workers Union (CWU), which represents more than 115,000 postal workers at Royal Mail, is planning further industrial action, with a fresh ballot due to open later this month.