More than 300 people in Scotland had to wait longer than 12 hours in hospital accident and emergency departments in the space of a month, figures have revealed.
In December there were 323 cases where patients in A&E had to wait this long, the highest number since July 2007, official statistics show.
National standards in Scotland set out that at least 98% of people in A&E should be either admitted or transferred for treatment, or discharged from hospital, within four hours.
Across Scotland just 90.3% of patients were dealt with within the target time in December, down from 95% in September and the lowest rate recorded since July 2007. In the NHS Lanarkshire area just 84.4% of patients in A&E were admitted, transferred of discharged within four hours during December.
Health Secretary Alex Neil said it had been a "busy winter" for the health service, with the "additional complexity" of dealing with norovirus.
"We want to have as many people as possible treated within four hours of their admission to accident and emergency and we have to recognise that while the vast majority of people are, improvements can still be made," he said. "There is no doubt that it was a busy winter with more emergency admissions than the same time last year and with the additional complexity of an early norovirus season.
Only four of Scotland's 14 regional health boards met the A&E waiting time target in December: NHS Orkney, NHS Shetland, NHS Tayside and NHS Western Isles.
The figures were disclosed the day after Mr Neil announced that emergency and urgent healthcare services are to be given a £50 million overhaul to try to improve treatment times and patient care. The money, available over three years, aims to change the way people are admitted to hospital, help them leave as soon as they are ready and improve links with other areas of healthcare so support is in place in the community.
Mr Neil said: "I have already made clear that we are taking significant action to improve unscheduled care in Scotland to make sure people are seen and treated in our hospitals and as quickly as possible. Changing the whole system takes time, which is why, as part of that investment package of £50 million, we will be doubling our winter planning fund to £6 million this year."
Opposition politicians hit out at the Scottish Government, with Tory health spokesman Jackson Carlaw criticising the "sloppy performance" on A&E waiting times. Mr Carlaw, also the Conservative deputy leader, said the problem of patients waiting too long in A&E departments is "getting progressively worse". Labour health spokeswoman Jackie Baillie demanded "real action rather than press releases and excuses" from ministers. "Patients are now paying the price for the SNP's failure to address the underlying problems in our NHS," she said.