Two teenage girls from Midhurst and one from Guildford have pleaded guilty to attacking a 14-year-old girl with a crowbar.
Brighton: Childcare On Labour Agenda
Working parents are being told they would receive 25 hours free childcare a week under a Labour Government.
Households where single or both parents hold down jobs currently only get 15 hours cover.
The help would be available for 3 and 4 year-olds and be funded by raising taxes on banks.
Mr Balls is expected to tell the conference at the Brighton Centre: "Childcare is a vital part of our economic infrastructure that, alongside family support and flexible working, should give parents the choice to stay at home with their children when they are very small and to balance work and family as they grow older.
"But for many families high childcare costs mean that it doesn't even add up to go to work. So to make work pay for families, we must act."
Mr Balls will make the announcement in a speech to activists where he will also attempt to underline the party's "iron discipline'' on spending in the run-up to the 2015 general election.
Meanwhile he today dismissed as "nonsense'' Conservative claims of a £27.9 billion "black hole'' in Labour's tax-and-spend plans, telling ITV1's Daybreak: "There are no uncosted spending commitments. There will be no more day-to-day borrowing from Labour in 2015.''
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