Hundreds of thousands of young children are at risk of falling behind before they start school because they do not have access to specially qualified early years workers, according to a charity.
Save The Children says that there is a shortage of around 11,000 early years teachers in England.
It argues that all young children should be in childcare that is led by graduate early years professionals to help ensure that they start school ready to learn.
The warning comes the week after Education Secretary Damian Hinds said it is a "persistent scandal" that youngsters are starting school unable to communicate in full sentence or read simple words.
He pledged to halve the numbers of youngsters beginning their schooling without the early speaking and reading skills they need at that age.
In his speech last week, Mr Hinds also said that the Government will be investing £20 million in training and developing early years professionals, focusing on disadvantaged areas.
Save The Children's analysis of data obtained through Freedom of Information requests concludes that around 10,731 nurseries, playgroups and children's centres that do not have staff with qualified teacher status (QTS), early years teacher status (EYTS) or early years professional status (EYPS).
QTS is typically held by school teachers, while EYTS and EYPS are broadly equivalent and focus specifically on early years education.
The charity estimates that this means that more than 300,000 children are at early years facilities where there is not a staff member with one of these accreditations.
Steven McIntosh, Save The Children director of UK poverty, said: "Children who start behind, stay behind.
"But high-quality childcare, led by graduate early years teachers, can ensure children are ready for school.
"So instead of lowering ambitions for childcare quality, the government should keep its promise to address the crisis in training, recruiting and retaining these underpaid and undervalued teachers.
"All of our little ones should have access to nursery care led by an early years teacher.
"Without action, we'll be letting down our next generation."
He added: "The Education Secretary has set out a major new ambition to improve social mobility, starting in the early years.
"Addressing this chronic shortage of skilled early years teachers must be at the forefront of this.
"But many early years teachers are leaving the profession or are close to retirement and the numbers starting training are plummeting.
"This is hardly surprising when official figures show that investment in promoting early years teacher training is less than 1% of what is spent on school teachers."
Save The Children said its own previous research had shown that children who are behind at age five are four times as likely to fall below the expected standard in reading at age 11 than their classmates who started their schooling at the right level.
In a speech on social mobility last week, Mr Hinds said: "It is a persistent scandal that we have children starting school not able to communicate in full sentences, not able to read simple words.
"This matters, because when you're behind from the start you rarely catch up. Your peers don't wait, the gap just widens.
"This has a huge impact on social mobility."
Research shows that more than a quarter of children start primary school lacking basic literacy skills, and youngsters with poor vocabulary at age five are more than twice as likely to be unemployed at age 34 as those with good vocab skills.
Nadhim Zahawi, children and families minister, said: "The quality of early years childcare has risen since 2010 with 94% of providers rated good or outstanding.
"This government wants every child to have the best start in life which is why we are investing more than any other in supporting early years education and childcare - around £6 billion a year by 2020."
He added: "Save the Children's claim is misleading, university study is just one route into the early years workforce.
"There are over 250,000 dedicated professionals in the private or voluntary early years workforce, with many coming from apprenticeship or on-the-job training routes."
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