More than 11,000 emergency calls in Wales took ambulances more than 20 minutes to respond to, according to figures obtained by Plaid Cymru.
One Category A call took 7 hours to reach in the Betsi Cadwaladr Health Board area while another in Cwm Taf took over four hours figures out today reveal.
Plaid Cymru submitted a Freedom of Information request to find out how many calls were responded to within 10 minutes - eight minutes is the target, 10-20 minutes, 20-30 minutes and more than 30 minutes.
Elin Jones, Plaid's Shadow Health spokesperson, said: "To have more than 11,000 of the most urgent calls taking more than double the target time of eight minutes to respond to is disturbing. These calls can be life and death situations where time is crucial.
Last month The Welsh Government said more needed to be done to raise the performance of ambulance response times. Figures released in May revealed they had missed their target for eleven months in a row.