Boris Johnson's pledge of 50,000 more nurses has been called "deceitful" by Labour and a "mixed message" by the Royal College of Nursing.
The prime minister made the announcement as he unveiled the Conservative election manifesto on Sunday.
The party said 18,500 of the 50,000 would come by encouraging existing nurses to stay in the profession and others to return; 12,500 would also be recruited from abroad.
Labour said it therefore meant only 19,000 posts would be filled by brand-new nurse trainees.
"The Conservatives' claim on nurses is frankly deceitful – the sums simply don't add up," said shadow health secretary Jonathan Ashworth.
"First we had Johnson's fake 40 new hospitals, now we have his fake 50,000 extra nurses."
The Royal College of Nursing (RCN) said an increased in numbers would be welcome, but pointed out that there is already a shortfall of 43,000 nurses in England alone.
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"Actually, what they need to do is recruit more in order to replace those who are already missing," said Patricia Marquis, the RCN's interim director for England.
She said the wording of the Tory pledge was also a "bit of a mixed message – with some about nurses or nursing staff – and it is a very different thing".
Registered nurses have a degree, but the RCN says there are many other nursing staff who help them deliver care.
Mr Johnson has also announced that nurse bursaries, which the Conservatives previously scrapped, would be reintroduced to try to get more recruits.
However, Ms Marquis said it only replaces "half of what they took away" because "they're planning to replace the maintenance grant but not pay for nursing students fees that was in place before".
Launching the manifesto in Telford on Sunday, Mr Johnson also said a Tory majority would also guarantee 50 million more GP appointments a year.
Sky News' economics editor, Ed Conway, analysed the Conservatives' spending pledges and found for every pound they want to spend by 2023/24, Labour will spend more than £28.
The NHS promises would mainly be paid for by not lowering corporation tax from 19% to 18%, as the Conservatives had previously promised.
The prime minister said the manifesto pledges could be achieved without raising income tax, VAT or national insurance contributions.
"That's our guarantee," he added.
Mr Johnson's keynote pledge is to "get Brexit done", and the evening before the manifesto launch he said the Withdrawal Agreement Bill would be put back to MPs before Christmas to sign off the deal before the 31 January deadline.
He also promised 20,000 more police officers and tougher sentencing, as well as an Australian-style immigration points-based system for EU and non-EU citizens.
Other pledges include:
- Getting rid of the Fixed-term Parliaments Act
- Raising the threshold for National Insurance contributions to £9,500 in 2020, with an "ultimate ambition" of £12,500
- Infrastructure investments – including better transport and tens of thousands of new homes
- £5bn in short-term funding for adult social care
- £74m more over three years in community care settings for people with learning disabilities and autism
- Free hospital car parking for disabled people, frequent outpatients, gravely ill patients, visitors and carers to long-term patients, as well as staff working out-of-hours shifts
- Doubling funding for dementia research, with an extra £83m a year
- £6.3bn to improve energy efficiency in 2.2 million disadvantaged homes – reducing bills by up to £750 a year
- Plant millions of trees
- £1bn for after-school and holiday childcare
- 250,000 more primary school children to get Read More – Source