The Southern Health Trust has said it is experiencing “significant issues” with its IT systems, which is impacting services at its sites including Craigavon and Daisy Hill hospitals.
Ambulances are being diverted while work continues to resolve the problems.
Patients are being warned not to come to appointments at any hospital or community service in the trust’s area on Wednesday.
People have also been asked to avoid coming to the hospital and other sites, but patient visiting is still possible.
