Five patients have tested positive for Covid-19 following two outbreaks at Craigavon Area Hospital.
The Southern Health and Social Care Trust has confirmed the latest cluster has been identified on the Haematology ward where cancer patients are treated.
Five patients have tested positive on the ward and one further in-patient was also identified. In total 12 patients on the ward have been tested, the trust said.
One member of staff working on the ward has also tested positive and three close staff contacts are self-isolating as a precaution.
The trust says the ward is now closed to admission.
“Trust staff are working closely with the Public Health Agency to manage the situation and the safety of both patients and staff remains a priority,” a statement said.
“There will be no routine visiting to the ward until further notice unless in exceptional circumstances.
“Virtual visiting by telephone or tablet device is available on request by contacting 077 7651 6419 between 9am and 5pm."
The families of patients are being contacted by the Southern Health Trust.
Earlier it emerged that 20 members of staff at the hospital were self-isolating after three colleagues working in the Respiratory Emergency Department tested positive for Covid-19.
A Southern Trust spokesman said: "At this stage it is understood that the infection may have transferred in a social setting i.e. not within the ED.
"Staff in the Emergency Department wear full personal protective equipment when treating patients therefore we do not believe there is any risk to patients at this time.
"The Emergency Department in Craigavon remains open but is extremely busy and we would urge the public only to attend if there is no other alternative."
A total of 47 new cases of Covid-19 have been confirmed across Northern Ireland in the last 24 hours, the Department of Health says.
DUP Upper Bann MP Carla Lockhart said she had "complete faith" the Southern Trust to deal with the outbreak.
She said she had spoken with the trust Chief Executive on Tuesday evening.
"My thoughts are with the staff and patients who have tested positive. It has been a long road for the staff working in the face of this virus as well as those patients who now face the dual concern of living with the virus and their illness," the DUP MP said.
"I appreciate the Chief Executive briefing me on the situation. I have complete faith in the trust to deal with this matter. I have seen first-hand the dedication of our health professionals throughout this pandemic. I wish both them and the patients affected a speedy recovery."