Children in the UK have suffered sexual abuse on an "industrial scale" with authorities failing to tackle the problem, David Cameron has said.
Outlining plans to tackle child sexual exploitation, the PM accused people and organisations of "walking on by".
Teachers, councillors and social workers in England and Wales who fail to protect children could face up to five years in jail under the proposals.
And police will now prioritise sexual exploitation as a "national threat".
This means such abuse will be treated in a similar way to serious and organised crime, with police forces, chief constables and police and crime commissioners having a duty to collaborate in order to protect children.
Abused 'over and over'
Mr Cameron, speaking at a summit called to address the issue after child exploitation scandals in Rotherham and Oxfordshire, said: "I think it's very important we take a step back and just recognise the horrific nature of what has happened in our country."
The proposals coincide with the release of a serious case review into abuse of children in Oxfordshire that found as many as 373 children may have been the victims of sexual grooming in the county over the past 16 years.
The investigation followed the prosecution of a sex gang of seven men who abused girls in Oxford between 2004 and 2012 and found that police and the local council made "many errors" in that case.
The new plans, which are going out to consultation, involve making it a criminal offence to wilfully neglect those at risk of, and victims of, child sexual abuse.
Social workers, education practitioners and local councillors would be covered by the sanction, which would be introduced as an extension of the crime of wilful neglect of patients by care workers in this year's Criminal Justice and Courts Act.
The prime minister added: "Young girls - and they are young girls - being abused over and over again on an industrial scale, being raped, being passed from one bunch of perpetrators to another bunch of perpetrators.
"And all the while this has happened with too many organisations and too many people walking on by.
"And we have got to really resolve that this stops here, it doesn't happen again and we recognise abuse for what it is."
Speaking to the BBC, he added that "if professionals fail, there need to be consequences".
The plans were unveiled at a meeting in Downing Street - attended by victims, survivors' groups, ministers, police chiefs, council leaders, child protection experts, and health and social care providers.
The proposals also include:
- Unlimited fines for individuals and organisations shown to have let children down
- A national helpline being set up to enable professionals to report bad practice
- Senior staff who leave councils after abuse councils having pay-offs "clawed back" if it is shown they failed to protect children under their responsibility
Labour has criticised the plans as a "missed opportunity", saying the government is not going far enough.
Analysis: Mark Easton, BBC Home Editor
It is now deemed a national threat akin to terrorism and major civil disorder but the issue of child sexual exploitation was not even a footnote in either the Conservative or Labour manifestos, nor indeed in the coalition agreement, at the last election.
And yet this is hardly a new problem. Experts have been warning for decades that up to a million children in Britain are victims of sexual abuse - each day.
If wilfully ignoring the problem is now to risk being sent to jail, some might argue our political leaders have questions to answer. Questions too about how today's strategy will improve matters on the front line.
While there is broad support for measures encouraging a greater priority for child sexual abuse, and measures to deal with what the prime minister called the 'walk-on-by' culture, will threatening social workers with jail if they fail in their duties encourage high quality applicants to join and stay in the profession?
Many councils report a high level of social work vacancies - particularly in more senior roles. So-called 'blame culture' is itself blamed for a shortage of qualified staff.
While more money was today announced for victim support groups, local authorities point out that since the election there's been a 20% rise in children referred to social services in England, a 42% in children given protection plans but a 40% real terms cut in council funding.
For many, the political focus on child sexual abuse is welcome, but long overdue.
Shadow home secretary Yvette Cooper called on the government to create a new offence of child exploitation, saying: "We need a radical overhaul of our child protection system, but I fear this is a missed opportunity to get all the reforms we need."
Labour also wants to see the introduction of mandatory reporting, which would impose a legal duty to report child abuse.
An independent report found that at least 1,400 children were sexually exploited in Rotherham by gangs of men who were predominantly of Pakistani origin between 1997 and 2013.
The report author Professor Alexis Jay said that girls as young as 11 were raped by "large numbers of male perpetrators".
Prof Jay, who took part in Tuesday's summit, said the issue had been made worse in some cases by the attitude of professionals.
She said: "Social workers were found to describe the issues as being lifestyle choices by some of the children and young people concerned.
"And the police, in my experience, certainly were extremely derogatory in the way they addressed and described the young people concerned."
'Earlier intervention needed'
David Greenwood, a solicitor who represents 39 victims of child sexual exploitation in Rotherham, said: "This is just the beginning of a war against exploiters. There are still many stories to emerge and abusers are still walking the streets.
"Without sustained effort, a generation of children are at risk of having their lives ruined."
David Simmonds, chairman of the Local Government Association's children and young people board, said "abuse needs to be taken seriously on a national level".
He said: "There is no question that those who are responsible for failing vulnerable children should be held to account... but we need to move on from the muddled situation councils currently face, so the detail of today's proposals is important to get right."
Maris Stratulis, England manager at the British Association of Social Workers said: "We totally support public accountability and transparency so welcome any measures that will make it easier for social workers and other professionals to whistle blow."