Thirty-three surgical procedures due to be carried out were cancelled as a result of a fire at a Londonderry hospital, the health minister said on 26 November 2012.
Responding to an urgent question, Edwin Poots said emergency services continued as normal at Altnagelvin Hospital.
Up to 120 patients in seven wards were evacuated on 23 November 2012 after a fire started on the roof.
The cause is under investigation, although Mr Poots said he believed it was "accidental and not related to the fabric of the building itself".
He said a comprehensive incident review would be carried out and that the Fire Service was following a particular line of inquiry.
The operation was treated as a "major incident" by the hospital and the Northern Ireland ambulance service.
Mr Poots said the evacuation had been "a truly integrated response" by the three emergency services.
He added that the vast majority of areas in the hospital were already back in operation, although patients in two wards remained where they had been relocated to elsewhere in the hospital while minor work was carried out.
The minister also said that the Western Trust was considering moving orthopaedic patients with heavy casts to better accommodation.
Sinn Fein Foyle MLA Maeve McLaughlin, who brought the question before the house, said the fire could have been "an awful tragedy" and said she had concerns over the health and safety of the building.
Mr Poots said he had invested £5m on this site over the last number of years.
The latest incident followed an electrical fire on 6 November which led to 20 patients being moved to other areas of the hospital.