NHS Wales has announced it is to block all incoming emails to its accounts until at least Monday, following a cyber attack on Friday which hit services in Scotland and England.
Ambulances were diverted and patients warned to avoid some A&E departments as IT failures affected up to 16 hospitals.
On Twitter, the Welsh NHS said it would review the situation after the weekend.
Outbound and internal emails will not be affected.
Home Secretary Amber Rudd insisted there was no evidence patient data had been released as part of the malware attack.
There have so far been no incidents in NHS Wales from the ransomware attack on NHS systems in England and Scotland. We have recently invested in upgrading IT to protect potentially vulnerable front-line NHS Wales systems. We have also introduced a national standard for IT security for all GP surgeries in Wales. We continue to monitor the situation closely.
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