Missed ambulance target 'disappointing'
Just under 57% of Welsh ambulances reached life-threatening incidents in eight minutes in April, short of their 65% target, figures show.
Ministers called the statistics, up on the 55% March figure, "disappointing".
The Conservatives said the "national scandal continues", Liberal Democrats called the situation "not right or fair".
The Welsh government said it expected NHS services to "work closely" together to improve patient care.
In a statement responding to the figures, Welsh ministers added: "While they show an improvement in performance over the month, we expect health boards to work closely with the ambulance service to ensure patients receive the care they require when they need it."
Shadow Health Minister Darren Millar said the statistics were "yet more evidence" of an "abysmal failure" by First Minister Carwyn Jones to meet key NHS performance targets.
Welsh Lib Dem leader Kirsty Williams said it was "not right or fair" that people in Wales had to accept "slower responses than patients across the border".
The target in England and Scotland is 75 percent.