Fewer Scots were seen in A&E within the four-hour target at the beginning of July than at any point in the previous six months, new figures show.
Statistics released by Public Health Scotland reveal that just 81.6% of those who attended emergency departments were seen and subsequently admitted to hospital or discharged within the four-hour period.
The Scottish Government’s target is at least 95%.
The figure, for the week ending July 4, is the lowest since the week of December 22, when it fell to 79.8% in the wake of a massive spike in coronavirus cases which would force Scotland back into lockdown on Boxing Day.
Broken down by NHS board, the figures vary from 70.5% seen within four hours in NHS Lanarkshire to 97.9% in NHS Orkney – although the latter included just 146 attendances at A&E.
The new low comes as recent weeks have seen a sharp decline in the number of people attending emergency departments.
Numbers dropped from 28,588 in the week ending June 6 to 26,080 less than a month later.
A spokeswoman for the Scottish Government said: “Scotland has had the best-performing core A&E departments in the whole of UK for more than six years.
“As restrictions begin to relax, we have seen a rise in admissions and non-Covid attendances, with levels returning to pre-Covid averages over recent weeks.
“To minimise pressures, last week the Cabinet Secretary announced £12 million in additional funding to health boards across Scotland to support non-Covid emergency care.
“This immediate action will help put measures in place to reduce waiting times for urgent or emergency treatment, with a focus on boosting staffing levels and available beds.”
But Scottish Liberal Democrat health spokesman Alex Cole-Hamilton said emergency departments are being put under “unsustainable pressure”.
“We know that the number of people having to self-isolate is spiralling. That’s a real danger to the wider health service and beyond,” he said.
“The staff left behind face a desperate situation, as the workload piles up but there aren’t enough people to cope with it.”
He added: “The Scottish Government need to come forward with concrete actions and urgent changes on isolation policies.
“That means a test and release system, as recommended by the Royal College of Surgeons and others.
“They must make sure Scotland has a functioning healthcare system.”