August was the worst month on record for waiting times at A&E, but still higher than more recent weekly figures.
Statistics released by Public Health Scotland (PHS) on Tuesday show just 77.8% of those who attended A&E in August were seen within the four-hour standard – despite a Government target of 95%.
The figure has been on a downward trend in recent months, falling from 88.7% in April.
During the month, 1410 people spent more than 12 hours in A&E without being seen and either admitted to hospital or discharged, while 5460 were there for eight hours or more.
The figures coincide with a crisis in the ambulance service, which has caused increased waiting times for those in need, prompting the Health Secretary, Humza Yousaf, to call in the military and fire service to ease the backlog.
Meanwhile, figures in recent weeks, which are reported more frequently than monthly figures, show a slight improvement in compliance with the standard, but the figure remains lower than for the whole of August.
In the week up to September 26, the standard was met for 76% of patients, which represented a slight rise from the previous week, when it was met in 74.4%.
During that week, 1191 people spent more than eight hours in A&E, while 343 were there for more than 12 hours.
Scottish Lib Dem leader Alex Cole-Hamilton said: “It’s only October.
“Winter pressures will make things so much worse.
“Staff need to know that their wellbeing won’t be sacrificed more than it has been already.
“They need a light at the end of the tunnel, and a cast iron guarantee that the health service will look after them, just as they have looked after us.
“If the Health Secretary can’t offer this, staff will undoubtedly head for the door.
“The government must also take full responsibility, instead of hiding behind the excuse of the pandemic.
“There needs to be a full independent review into all unnecessary deaths caused by this crisis, so that the government does not repeat its mistakes.”