Data for the week ending February 6 showed 74.4 per cent of patients in A&E were admitted to hospital, transferred or discharged within four hours – down from 75.6 per cent of patients the previous week and well below the Scottish Government target of 95 per cent.
Staff in A&E units dealt with 23,429 cases over the seven days, with 1,346 patients there for eight hours or more.
Meanwhile, a total of 498 patients spent over 12 hours in an A&E.
The Scottish Government insisted there had been a “marked improvement” in the performance of emergency departments when compared to earlier this year.
But opposition politicians branded the situation “wholly unacceptable” as they warned long waits for treatment could be “downright dangerous”.
The Tory stated: “Week after week Humza Yousaf’s continued inaction is failing our NHS. These A&E waiting times are once again wholly unacceptable.
“Our frontline NHS staff are working flat out, but they are being badly let down by the SNP Government who haven’t stepped up to support them.
“Humza Yousaf needs to start showing the leadership required if A&E waiting times are ever again going to be brought under control.”
Labour health spokeswoman Jackie Baillie said the latest weekly figures were a “stark reminder that the crisis engulfing our A&E is far from over”.
Ms Baillie, also Scottish Labour deputy leader, hit out, saying: “Not only are things not improving, but they are getting worse once again, despite the very best efforts of the hard-working NHS staff.
“Hundreds of people being stranded for over 12 hours when seeking urgent help is downright dangerous, and it is a damning indictment of the SNP’s response to this crisis.
“If the SNP are going to ease the pressure on our emergency rooms, they need to free up capacity by tackling delayed discharge – but this has soared to its highest point since the pandemic began.
“We cannot let chaos become the new normal in our NHS. The SNP must make sure health and social care services across Scotland can cope, or lives will be lost.”
Scottish Liberal Democrat leader, Alex Cole-Hamilton, was also critical of the SNP administration, pointing out the A&E waiting times target “is being missed week after week despite NHS staff continuing to work around the clock”.
A Scottish Government spokeswoman said: “A&E waits continue to show a marked improvement on the situation from the turn of the year.
“Almost three-quarters of patients were seen within the four-hour target and this is reflective of the improvements we are seeing in staff absence and the series of measures implemented to minimise pressures across our A&E services.”
The spokeswoman stressed “NHS staff continue to face unprecedented pressures as they work to respond to the pandemic whilst continuing to provide vital treatment and optimal patient care”.