A major IT and phone systems failure has wiped out A&E services at two major west London hospitals.
The Hillingdon Hospitals NHS Foundation Trust issued a statement on Tuesday morning, which said part of the phone and IT network is down.
"To ensure patient safety, the trust has had to suspend non-urgent procedures until we are able to resolve the issue," the statement said.
A&E emergencies are being diverted to other hospitals.
CT scans at 11am have been cancelled and will be rescheduled as soon as possible, the trust said.
Outpatient appointments are all going ahead as planned.
The trust, which was last rated by the Care Quality Commission in August 2015, is rated as "requires improvement".
Hillingdon Hospital, in Pield Heath Road in Uxbridge, is the only acute hospital in the area, according to the trust's website, with a busy A&E department, inpatients, day surgery and outpatients clinic.
Mount Vernon Hospital, in Rickmansworth Road, Northwood, contains a diagnostic and treatment centre, the Princess Christian Unit, four operating theatres for elective surgery and outpatient services.
Between them, the hospitals serve a catchment population of more than 350,000 across Hillingdon, Ealing, Harrow, Buckinghamshire and Hertfordshire.
Anyone with concerns can call the hospital switchboard on 01895 238282.
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