Nurseries in England's poorest areas are facing closure because of a shortfall in government funding, a charity has said.
A report by the Early Years Alliance (EYA) found 17% of childcare providers surveyed in the most deprived areas of the country "anticipate closure in the next twelve months".
Some nurseries said they had lowered the quality of food given to children.
The Department for Education said it spent £3.5bn a year on early education.
Since September 2017, most working parents in England have been entitled to a scheme offering 30 hours of free care for children aged three to four during term time.
The government pays a national average of £4.98 per hour for places to local authorities but childcare providers have said this does not cover their costs.
Neil Leitch, chief executive of the EYA, said the nursery sector was "in crisis".
"How much bigger does the early years funding shortfall have to grow before the government acts?" he asked.
"Thousands of providers have closed, many more are charging for things that were previously free and now we see the impact this is likely to have on the poorest children in the country."
The survey of more than 350 nurseries and childminders found 43% of providers had been forced to cut back on learning resources and 19% said they had lowered the quality of food they gave to children.
Paula Williams, who runs a nursery in Bradford, said it could be forced to close if government funding did not increase.
All of the 48 children at the centre are supported by the government's scheme, with no fee-paying students. Ms Williams said 80% of the budget went on staff costs.
"Our funding went down yet our costs have all increased because national living and minimum wage is going up year on year and also we had to start paying pensions for all staff.
"Further forward it's getting tighter because next year the minimum wage will go up again and our funding is stagnant, it's not increasing," she said.
Alia Kauser, whose son attends the nursery, described early years learning as "really important".
"I've realised the change in my son Ismail," she said.
"Before he was not as talkative and didn't want to get involved but now when I see him, when I pick him up from nursery he's totally engaged."
The Department for Education said it provided "a significant package of childcare to parents and carers".
"Our Early Years National Funding Formula allocates our funding to local authorities fairly and transparently," it said.
"We recognise the need to keep our evidence base on costs up-to-date and we continue to monitor the provider market closely through a range of research projects."