Many parents could face prosecution for leaving their children home alone during the summer holidays, a children's charity has warned.
The Children's Legal Centre is calling for clarification of existing law, which fails to specify at what age children can be left on their own.
Parents who fall foul of the law can face up to 10 years in prison.
The government says children have different levels of maturity and responsibility at different ages.
Charities predict that more than a million children could be left alone this summer because childcare costs are too high for some families.
Children's Legal Centre (CLC) spokesman Dominic Bascombe told BBC News: "The law says it can be an offence and this is why we're advising parents that they need to be careful when they're leaving children alone at home during the holidays."
Under the Children and Young Persons Act 1933, parents in England and Wales can be prosecuted for wilful neglect if they leave a child unsupervised "in a manner likely to cause unnecessary suffering or injury to health".
*Consider the age of the child
*Take into account the child's maturity and understanding
*Think about the location the child will be placed
*Will the child be on their own?
The law does not give details of what amounts to wilful neglect, unnecessary suffering or injury to health - but punishment can range from a fine to 10 years imprisonment.
A similar law applies to Scotland under an act passed in 1937.
The CLC and children's charity the NSPCC advise that children should not be left with a child minder younger than 16.
Mr Bascombe says the age of a child does not necessarily reflect how responsible they are.
"A child of nine could be more mature than a child of 14. Each child has to be taken on their own individual merit."
He also says that if a child is left alone or with a sibling, parents should not be more than 15 minutes away, children should know how to get help and know what to do in the case of an emergency.
Working mother Joyce Hazard, from Melton Mowbray, told BBC News why she leaves her 14-year-old daughter home alone during school holidays: "We have no alternative. Both myself and my husband work full time.
"For the school holidays we've done a quick calculation - there are 13 and a half weeks of school holidays, that's 67 days and that's more than my husband and I get in annual leave."
She believes the guidelines are unworkable: "I think they're unreasonable.
"They're very unclear as to when you can leave a child alone and there's no thought or consideration on what the impact is going to be on the huge majority of working parents."
Several high-profile cases of child abandonment have reached the courts.
Earlier this year a mother was given a suspended jail sentence for leaving her 14-year-old daughter alone for six weeks while she went abroad to see her boyfriend.
In Bedfordshire two children, aged seven and 11, were removed from their family home after police suspected they had been abandoned while their parents went on holiday to the tropical island of Curacao.
The NSPCC say that the mental as well as physical welfare of the child should be taken into consideration.
Spokesman for the charity Chris Cloke says: "We know that children who are left for quite a short period of time feel lonely and isolated and they don't like it. They like to have company."
A spokesman for The Department for Children, Schools and Families says no age is specified because each child has a different level of maturity and sense of responsibility.
He said: "It is very difficult to offer a 'one size fits all' benchmark for when children can be left at home unsupervised.
"Because of this, we expect parents to use their own judgement in respect of their children or children they look after, whether they can be left at home unsupervised and how long for."