UKIP pledges pay rises and extra cash for NHS
UKIP leader Nigel Farage said his party was "committed" to a free NHS paid for by taxes as he set out plans to spend an extra £3bn per year on the service.
The party said it would end hospital parking charges and give NHS staff a pay rise.
UKIP would require overseas migrants to prove they have insurance cover on arrival in the UK to end what it calls "health tourism".
Labour said UKIP had "longstanding support" for NHS privatisation.
Mr Farage has previously proposed an "insurance-based system of healthcare".
He has since said his idea was rejected by the rest of the party.
At the party's first big policy launch of the general election campaign, Mr Farage said: "UKIP is committed to an NHS that is free at the point of access and paid for out of taxation, full stop.
"But just because we believe in the NHS it doesn't mean we can't be critical of certain aspects of it. Certainly what we have seen over the last few years is a huge increase in money but not always a compensating increase in productivity."
Analysis by Robin Brant, BBC political correspondent
The NHS is a double-edged sword for UKIP.
Playing up a raft of new (ish) health policies - at the latest in the party's series of set-piece speeches in the run up to the general election - is designed to broaden its appeal.
But it also highlights what has been, and is likely to continue to be after the election, a controversial area for UKIP.
There have been internal rows over Nigel Farage's support for a private insurance model. He lost that argument with others at the top of the party, but Labour says he hasn't lost the belief in the need for such radical change.
On the contrary, UKIP believes strong support for the NHS - with that extra £3bn a year spending pledge - plays well in areas where the party is trying to damage Ed Miliband's chances in the north of England.
Mr Farage said parking charges were a "tax on health" affecting patients and their families.
And he said demanding health insurance proof from requiring migrants workers, overseas visitors and students was "really about common sense".
UKIP said the requirement, which would expire once someone has lived in the UK for five years, would save "up to £2bn".
Speaking on BBC Radio 4's Today programme, UKIP's health spokeswoman Louise Bours said health insurance would be a condition of entry into the UK.
She said it should not be "beyond the wit of man" to find a way to make the system work at the UK's borders, adding that the structure of the scheme would be worked out when in government.
Labour's shadow minister without portfolio Jon Trickett said: "Nigel Farage has made clear that he personally believes in increased NHS privatisation, so a single speech cannot hide their real agenda."