The massive inquiry into the Rotherham sex abuse scandal could run until at least 2018 and has so far identified 300 suspects, it emerged yesterday.

Investigators say the number of possible offenders is changing on a ‘daily basis’ and they suspect ‘thousands of offences’ have been committed.

The team has seized 92 boxes containing several thousand files and identified more than 3,300 lines of inquiry.

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Probe: National Crime Agency senior investigating officer Steve Baldwin (left) said the 1,400 victims who were identified by Professor Alexis Jay (right) last year in her damning report was a 'very good estimate'

The suspects are ‘predominantly’ Asian men from the South Yorkshire town and include two who have worked for the council. Their victims are mainly white, British, underage and ‘vulnerable’ girls.

Operation Stovewood is currently costing up to £5million every year, and is still likely to be ongoing in three years’ time – putting the total bill for the inquiry at around £15million.

So far the inquiry has backed an original estimate that 1,400 girls were abused in Rotherham during a 16-year period from 1997 to 2013 – with police and social workers accused of being too concerned about being labelled racist to speak out about the crimes.

Last night children’s charities demanded that the men should be brought to justice.

Barnardo’s chief executive Javed Khan said: ‘Because so many vulnerable children were ignored by the authorities, groomers got away with exploiting them for years.

‘Ensuring the cases against groomers go to trial is vital in giving sexually exploited children confidence that the justice system does work for them; that if they come forward, they will be believed and supported.’

Karen Froggatt, from the charity Victim Support, said: ‘The scale of sexual exploitation against children in Rotherham is appalling. We know from supporting many of these victims just how devastating and long lasting an impact it has.

‘Our priority is to make sure that the victims of this horrendous abuse in Rotherham, and elsewhere in the country, get the respect they deserve and the support that they need as soon as possible.’

Damning: The report published last year was highly critical of police and local authority actions over 16 years, shocked the nation and led to a wave of high profile resignations. Rotherham Council's offices are pictured

The investigation was launched six months ago by the National Crime Agency (NCA) – dubbed Britain’s FBI. The NCA inquiry is in addition to two investigations by South Yorkshire Police.

One, relating to offences between 1990 and 2003, has led to 16 arrests and three men being charged. The other covers the years after 2005, involves girls as young as 12 and has led to one person being charged and six arrests so far. Yesterday details of the NCA inquiry were revealed at a Press conference in Sheffield.

The scale of sexual exploitation against children in Rotherham is appalling Karen Froggatt, Victim Support

The team of 32 officers has been collecting a vast amount of documentary evidence and carrying out research.

They are yet to formally interview the hundreds of victims and suspects. However NCA director Trevor Pearce said that despite the difficulties of investigating crimes committed many years ago, his team had the ‘common desire to bring those responsible for harming children in the town to justice’.

He warned: ‘No one who has abused children should rest easy believing they will not be held accountable because of the passage of time.’

Yesterday Steve Baldwin, the NCA’s chief investigating officer, said: ‘We will process this investigation as quickly as professionally possible but it is complex. Much of the information we have is not yet in a format that makes it easy to analyse.

‘We will use the information as a starting point for developing intelligence and evidence. Given the amount of victims there are, there is potential to identify thousands of offences.’

Rotherham scandal: The NCA confirmed most of the potential suspects were Asian men and most of the victims were white British girls and young women

Mr Baldwin went on to stress that he was not concerned about the inquiry’s racial sensitivities, and confirmed that the ‘majority’ of suspects ‘appear to be of Asian appearance’.

He added: ‘It has been widely reported the ethnicity of offenders was largely of Asian background, but I treat everyone who has abused children as being offenders and I will thoroughly investigate anyone who I think might have been involved in the horrendous abuse in Rotherham over the years.’

This latest police investigation may relate to historical cases but still leaves the feeling that the dark shadow of abuse has not been lifted from the city. NSPCC spoksesman

Mr Baldwin said a previous estimate which said there could be 1,400 victims was a ‘very good assessment’. And he promised to listen to potential victims to prove his team ‘deserved the trust and confidence of others’.

The investigator also confirmed that many of the potential offenders were thought to have operated in ‘organised groups preying on vulnerable children’.

He added: ‘We will prioritise action against suspects who continue to pose a risk of harm today and those who have caused the most harm in the past. I know there are more victims yet to be identified for us to reach out to.’

A NSPCC spokesman said yesterday: ‘The scale of child sexual abuse in Rotherham that continues to be uncovered is staggering.

‘Eight years after the first victims of widespread grooming were identified the scandal is still rumbling on. This latest police investigation may relate to historical cases but still leaves the feeling that the dark shadow of abuse has not been lifted from the city.