Waiting times for hospital accident and emergency departments in Wales have improved slightly, but are still short of the expected standards.
Last month about 12% of patients waited four hours or more to be seen after arriving in A&E.
The Welsh Government said the vast majority of patients were treated within the target time.
The Conservatives said it was "simply unacceptable" for people to wait longer than four hours.
Official figures show 88.1% of patients spent under four hours from arrival until admission, transfer or discharge in April - up 1% on February. The long standing target is 95%.
In the same month, 97.7% spent fewer than eight hours from arrival until admission, transfer or discharge - also up 1% on the previous month. The target has been 99%.
The figures show some variation in performance across Wales.
The worst performing major A&E departments were in Cardiff and the Vale, with 79.6% of patients dealt with in four hours.
The best performing were in Cwm Taf, where 91.2% were dealt with in four hours.
Conservative Darren Millar said the figures showed the scale of the challenge facing Health Minister Lesley Griffiths, who was appointed after this month's assembly election.
He said: "It is simply unacceptable to expect people to wait over four hours and in some cases over eight hours to be seen by a clinician.
"Excessive waits in A&E departments can be distressing and uncomfortable especially for the elderly, young children and the chronically ill."
The Welsh Government said April saw the biggest number of people attend A&E for almost a year and that the "vast majority" of the nearly 70,000 people at emergency departments were treated within the target times.
A spokesman said: "However, there will be times where patients may need to wait longer as they may need tests and scans to help staff decide on the best course of treatment. We expect all patients to be treated in order of clinical priority.
"These statistics show that more people are being seen within the target time but we need to see further improvements over the coming months."
In an attempt to relieve pressure on A&E, a campaign was launched earlier this year - called Choose Well - encouraging people to use the most appropriate health service for their needs.