New figures show that 106 patients who attended an A&E in Ayrshire and Arran earlier this month waited more than 12 hours for treatment.
A further 170 were also forced to wait more than eight hours, according to the stats.
The figures come from Public Health Scotland and cover the week ending Sunday, January 9.
They also show that, of the 1426 patients who presented at an Ayrshire and Arran A&E, only 73.2 per cent were either admitted, transferred or discharged within four hours.
Since 2015, the Scottish Government’s target is to ensure 95 per cent of patients are seen within the four-hour standard.
However, the figures show that 26.8 per cent of local patients are facing significant waits before their injuries or ailments are treated.
South Scotland Labour MSP Colin Smyth said the figures were “deeply worrying.”
He said: “Week after week we have seen all-time lows in A&E services but the SNP government has failed to act.
“The Scottish Government’s lack of action in the face of this crisis has been nothing short of a dereliction of duty.”
South Scotland Conservative MSP Brian Whittle labelled the figures a “damning indictment” of the NHS under Health Secretary Humza Yousaf and the SNP.
Mr Whittle said: “He has had months to get a grip of the worsening situation in our A&E departments and he’s failed. There’s no sign of a credible strategy to give NHS staff the support they need or to remobilise wider NHS services for the thousands of patients waiting for help.”
Tory colleague, MSP Sharon Dowey said the figures were “absolutely appalling,” adding: “Humza Yousaf has had months to get a grip of this crisis in our A&E departments in NHS Ayrshire and Arran, yet he has failed to do so.”
A Scottish Government spokesperson said: “Scotland’s core A&E departments continue to outperform those in the rest of the UK, and have done so for more than six years.
“To support the workforce and maximise capacity we have introduced a range of measures including new remote monitoring tools to support people with COVID-19 to stay safely at home.
“We have also expanded capacity in NHS24 so they can help more people and further alleviate pressures on the rest of NHS and social care.”
Earlier this month NHS Ayrshire and Arran admitted that they faced “significant pressures” due to the Covid-19 situation.
They had to contend with staff shortages after more than 270 were forced to self isolate following positive Covid tests.
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