Wales has the UK's slowest ambulance response times to emergency calls, figures obtained by BBC News suggest.
The average response time in Wales last year was eight minutes and 47 seconds, against a benchmark of eight minutes.
Wales also had the highest proportion of calls which took longer than both eight minutes and 15 minutes to receive a response.
The Welsh Ambulance Service Trust said improvements had been made but more work was needed.
The trust said the service recorded its best "all-Wales performance" in April, with 70% of emergency responses arriving within eight minutes.
The assembly government said ambulance service performances could not easily be compared due to the "different geography and demography" of the UK.
The fastest responses last year were in London and the south east of England, with an average response time of six minutes and 22 seconds for category A emergency calls.
The figures were released to BBC News through a freedom of information request.
They included 13 of the 15 ambulance services in the UK, although details were unavailable for the East Midlands and the Isle of Wight.
The service in Scotland only provided an average response time, which was seven minutes and 12 seconds in 2009.
The Welsh Ambulance Service Trust said it covered an area "full of varied demographic challenges compared to other UK ambulance services".
It said: "In 2007 we introduced the five-year 'time to make a difference' modernisation programme to meet these challenges head on and improve our service to the people of Wales.
"Welsh Assembly Government-funded automatic vehicle locating system technology has improved the effectiveness of our response to life-threatening and serious emergencies, and the introduction of new initiatives has also helped improve the appropriateness of our response.
"The all-Wales performance against the eight-minute standard has steadily improved, reaching 65% of life-threatening emergencies in eight minutes during eight of the last 12 months.
"In April this year we achieved our highest all-Wales performance ever of 70% of life-threatening calls within eight minutes.
"The trust recognises that although improvements have been made, more work is needed to consistently maintain and improve the quality of care given to patients at a local level across Wales."
Last summer, the service was criticised by a former head Roger Thayne who resigned in 2006 claiming it needed major investment and was putting lives at risk.
Health Minister Edwina Hart said at the time that staff were doing all they could, but there were "a number of underlying issues".
These included fluctuating performance due to seasonal pressures, overworked staff and, while sickness levels had fallen, they were still too high.
A Welsh Assembly Government spokesperson said: "Performance of the ambulance services across the UK cannot be easily compared given the different geography and demography and its impact on service delivery.
"While we are pleased to see the improvements made by the Welsh Ambulance Service Trust over the past year, we recognise that there is still some way to go and the trust is working hard to ensure that further improvements are delivered and sustained."