Waikato DHB's chief executive says the board will not pay ransom in order to quell the cyberattack crippling the region's health services.
"The government position is that we don't pay ransom," Dr Kevin Snee told media on Saturday afternoon.
The ransomware attack on Tuesday crashed Waikato DHB's IT systems including computers and phones, affecting Waikato, Thames, Tokoroa, Te Kuiti and Taumarunui hospitals.
Dr Snee says the system can be fixed by using backups to rebuild it.
"We have backups for all our files so that's what we would use to rebuild a system so it is imminent to do that and we're working towards building our system back."
He says information systems teams are working in shifts around the clock and the incident control team were on hand throughout the weekend, but still a fix was "proving complex".
"We expect this to run for a further week and possibly beyond. Investigation into this type of cybersecurity events is challenging and complex.
"Hospitals are complex organizations with many hundreds of servers serving over 400,000 population with 8000 staff over many sites."
Despite estimates the system will be working towards the end of next week, Dr Snee says it's not currently possible to provide a "clear timeline'' - and even when it is back up and running there may still be challenges.
"Even when we are back up and running fully there will still then be quite a recovery period afterwards. Because obviously, you can imagine there's a lot of things to enter that are now in writing, and some patient information for example that will need to be re-entered on the system."
He says patients safety and service remains the "number one priority".
Adding that about 80 percent of elective surgeries were still going ahead and around 80 percent of outpatients were still being seen too.
He said there were "just over 100" elective surgeries going ahead per day at Waikato Hospital with about 20 cancelled. He was unable to comment on numbers at other hospitals such as Thames.
He urged those who have appointments within the Waikato DHB to call ahead to check they were still happening but to be prepared for long wait times due to clogged phone lines.
This week doctors at Waikato Hospital have been reverting to whiteboards and hard copy records to continue treating patients.