Covid in Scotland: NHS Lanarkshire halts non-urgent procedures
NHS Lanarkshire is the latest health board to halt non-urgent procedures due to rising demands on the NHS.
It said staff at its three hospitals were facing "unprecedented pressures".
Two weeks ago health boards covering Lothian, Ayrshire and Arran, the Borders and Highland took similar decisions.
They have all blamed staff shortages and rising patient demand, leading to longer waiting times in accident and emergency.
Dr John Keaney, NHS Lanarkshire's acute medical director, said staff at the Hairmyres, Monklands and Wishaw hospitals were "struggling to cope".
"We are facing relentless pressures, bed shortages and staff shortages due to sickness, stress and self-isolation," he said.
"Unfortunately we are having to postpone the majority of non-urgent procedures and I would like to apologise to those patients affected."
Those affected will receive a text message, letter or voice message, but a small number of clinically urgent appointments will go ahead as scheduled.
"Cancelling this inpatient activity will release bed capacity and staff to support our A&E department which is currently seeing an unprecedented level of activity," Dr Keaney added.
Coronavirus cases exceeded 5,000 on Wednesday - a record high - but doctors have told the BBC that the pressure on the NHS is not necessarily coming from Covid patients.
Instead, more people are being admitted with other more complex, advanced disease, having put off seeking treatment during the lockdowns.
NHS Lanarkshire said there were more than 700 patients at its three hospitals on Monday - and this level of activity had been sustained over weeks and months
Dr Keaney asked people to avoid A&E unless they have a life-threatening condition.
"We continue to see people attend A&E for conditions that would be best treated elsewhere," he said. "We are asking people to please keep our A&E departments safe for those who need critical care.
"If you think you need to attend A&E but it's not life-threatening, you should consider the alternatives. You can call NHS 24 on 111 day or night, where you will be directed to the right NHS service. If you just need health care advice, then please use the NHS Inform website."