The Shadow Health Minister Darren Millar described the figures about ambulance response times in 2012 as "shocking" and "inexcusable".
He said "we have a big problem in the way that our emergency care system is operating in Wales", both in terms of ambulances and A&E departments.
The Welsh Government has commissioned a review into how emergency response times can be improved, which will report next month.
More top news
Two staff members at an education referral unit have been charged with child cruelty offences allegedly involving dozens of pupils.
Cardiff's Neonatal Intensive Care Unit has been closed since Thursday due to poor 'infection control measures', a health council has said.
Welcome to the Newsweek Quiz - where we'll be testing your knowledge from the last seven days of news in Wales.