Spending on the NHS has been rising
The Conservatives have clashed with the government over a report into the state of the NHS.
Labour has hailed a think tank's review of 11 health systems as evidence its health service reforms are working.
The Commonwealth Fund report, based on a poll of more than 10,000 doctors, suggested the NHS compared favourably with services in other countries.
But the Tories said data on the numbers surviving disease showed the health service had got worse under Labour.
The clash marks the start of the struggle by the two parties to portray themselves as the champion of the NHS in the lead up to the election.
More than half of GPs say the quality of care has improved - the highest number in any country surveyed
Just a fifth said patients faced long waits to see a specialist - the lowest figure from the 11 nations
Nearly all reported using electronic records
The US-based Commonwealth Fund's review focuses on processes, such as waiting times and use of technology, which have come to define the government's approach over the past decade.
The Tory data - from the Organisation of Economic Co-operation and Development - covers outcomes, such as success in treating disease.
The fund's report, which compared countries such as the US, Australia, France and Germany, showed GPs in the UK were the most likely to say their health service was improving - 51% did so.
The UK also scored highly on access to specialist care, out-of-hours provision and use of electronic records.
Health Secretary Andy Burnham, who has gone to the US for the launch of the report, said: "This is an important moment for the NHS.
"The journey to overhaul the quality of care over the last 10 years has paid off."
And he added the Tories represented a "danger" to the NHS.
But the Tories have countered by highlighting data published earlier this summer.
It showed that in terms of deaths from treatable disease, the UK had slipped from 9th to 10th in Europe.
It ranked in the worst quarter of European countries on deaths from breast cancer, while deaths from lung disease were 75% higher than the European average.
Deaths from lung disease in the UK are 75% higher than the European average
People are more than twice as likely to die of a heart attack in the UK than in France, the best performing European nation for heart care
The UK ranks in the bottom 25% of European countries for survival rates from breast cancer
Shadow health secretary Andrew Lansley said: "Labour have trebled the amount we spend on the NHS, but these figures show that they have failed to get taxpayers a good return for their investment.
"That means lives lost prematurely and avoidably."
And Lib Dem health spokesman Norman Lamb said: "While Andy Burnham may try to spin these figures as a great triumph, he cannot ignore the fact that the UK remains behind much of the developed world when it comes to cancer and stroke survival rates, we have a spiralling public health crisis and health inequalities are getting worse."
Nigel Edwards, of the NHS Confederation - which represents managers - said the NHS had been making great strides, but added there were still areas, such as cancer treatment, where there was "still some way to go".
And the British Medical Association warned the recession may lead to the health service suffering.
A spokesman said: "The financial crisis means that politicians are falling over themselves to talk about efficiency savings, and we must not allow frontline services to be targeted."