Just 41 per cent of patients at Forth Valley Royal Hospital were seen within four hours in the week to October 10, a drop of almost ten percentage points on the previous week.
It is also the lowest figure on record for any hospital, following the previous low set by Glasgow’s Queen Elizabeth University Hospital in September.
The overall figure across Scotland was 71.3 per cent, the same as the week before, with some health boards showing slight improvement.
But across the country both the number of patients waiting longer than eight hours, and the number waiting longer than 12 hours, increased.
Opposition politicians have lambasted the health secretary over the new figures.
Scottish Labour deputy leader and health spokesperson Jackie Baillie said: “With the army being called in to support several health boards, the Health Secretary cannot continue to pretend everything is rosy… Things have to change now, or else we face a winter of chaos.”
Scottish Conservative Shadow Health Secretary Dr Sandesh Gulhane MSP, said: “Our A&E departments are in complete crisis and have been for far too long on Humza Yousaf’s watch. More and more health boards are having to call on support from our UK Armed Forces due to his continued inaction."
Liberal Democrat leader Alex Cole-Hamilton added: “This crisis has escalated to levels that would have been unimaginable just months ago. These waiting times are not sustainable, and staff cannot and should not be expected to work through another six months of this.”
A spokesperson for NHS Forth Valley said: “Forth Valley Royal Hospital, like many hospitals across Scotland, is exceptionally busy and we have seen high numbers of attendances at our Emergency Department over the last few weeks and many seriously ill patients who require to be admitted for treatment.
"As a result, some patients may have to wait for longer periods of time in the Emergency Department until an inpatient bed becomes available.
"Staff are doing everything possible to reduce delays and we would like to take this opportunity to apologise to anyone who has experienced a longer wait to be seen at this very challenging time.”