Scotland’s accident and emergency waiting time performance declined in early August, with 66.5% of those who attended emergency departments being admitted, transferred or discharged within four hours.
The latest weekly figure is down from 69.0% the previous week.
Public Health Scotland’s data also gave performance figures for all A&E sites during the month of June.
During this month, performance against the four-hour standard was at 72.6%, with a total of 137,183 unplanned attendances in A&E.
For the week ending August 6, there were 25,123 unplanned attendances at emergency departments.
Some 16,697, or 66.5%, were seen, resulting in a subsequent admission, transfer or discharge within four hours.
A Scottish Government spokesman said: “We are determined to see improvement in emergency department performance and continue to work closely with the health boards facing the greatest challenges in A&E to drive down waiting times and improve services for patients and staff.
“Performance is still not where it needs to be and there is continued disparity in performance both between health boards and individual sites.
“Hospital bed occupancy continues to be a major factor impacting on performance, which is why we are working to reduced instances of delayed discharge and are continuing to expand our Hospital at Home capacity.”
Scottish Conservative health spokesman Dr Sandesh Gulhane said: “It is utterly appalling that a third of patients are now routinely waiting over four hours to be seen in Scotland’s A&E departments.
“They are a damning reflection of the SNP’s shambolic mismanagement of our NHS and even at the height of the summer period, waiting times are worsening.
“Despite the best efforts of my dedicated colleagues on the front line, patients are still facing intolerable delays at A&E.
“Thousands are waiting over eight hours to be seen, while hundreds are suffering scandalous waits of half a day or more.”
Scottish Liberal Democrat leader Alex Cole-Hamilton said: “It has been over three years since the Scottish Government last met its target for 95% of attendees to be seen within four hours.
“There is no shortage of goodwill and dedication on the part of NHS staff, but they don’t have the beds, safe staffing and resources they need.
“As health secretary Humza Yousaf comprehensively failed to get to grips with the crisis in our A&E departments.