Politicians must "fully commit" to funding children's social care ahead of the General Election, local government leaders have said.
Pressures facing children's services are becoming unsustainable, with a £2 billion funding gap expected to open by 2020, analysis by the Local Government Association (LGA) shows.
It says the gap will continue to grow unless action is taken to reduce the number of families relying on the system for support.
Councillor Richard Watts (pictured), chairman of the LGA's children and young people board, said: "Services caring for and protecting vulnerable children are now, in many areas, being pushed to breaking point.
"Ahead of the General Election all political parties must commit to fully funding children's social care to ensure vulnerable children get the appropriate support and protection they need.
"Councils are committed to providing the best possible support to vulnerable children and their families, but the demand for children's social care services has more than doubled and is stretching local authority resources."
Councils have faced a surge in demand for support over recent years.
More than 170,000 children were subject to child protection inquiries in 2015/16, compared with 71,800 in 2005/06, and the number of children on formal child protection plans has increased by almost 24,000 over the same period.
The LGA says continuing reductions to local authority budgets are forcing many areas to make difficult decisions about how to allocate resources.
Mr Watts added: "With councils facing a £2 billion funding gap for children's services in the next three years they have responded by reducing costs and finding new ways to deliver services.
"But there are very few savings left to find without having a real and lasting impact upon crucial services that many children and families across the country desperately rely on.
"Early intervention can help to limit the need for children to enter the social care system, lay the groundwork for improved performance at school and even help to ease future pressure on adult social care by reducing the pressure on services for vulnerable adults.
"However councils are in a difficult situation where they are struggling to invest in this vital early help and support."
Action for Children said councils were "caught between a rock and a hard place" as they had limited resources to meet rising demand to support disadvantaged children.
The charity's director, Kate Mulley, said: "Children's centres, short breaks for disabled children and information and advice for young people are just some of the services affected.
"Government funding for these services will fall by 71%, from £3.2 billion to less than £1 billion between 2010 and 2020.
"We are calling on the next government to provide essential funding to sustain vital services that help to build a better future for children in communities across the UK."
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