The National Crime Agency has asked for more detectives and investigators to work on child sexual exploitation offences in Rotherham.
There is a 144-strong police team working on Operation Stovewood, which is looking into historic child sexual exploitation offences in Rotherham between 1997 and 2013, but the National Crime Agency wants to increase the number to 200.
The NCA launched its operation in the wake of a report in 2014 which found that 1,400 children had been abused for over a decade while those in authority failed to act.
Professor Alexis Jay, who was commissioned to write the report by Rotherham Council, found that men of largely Pakistani heritage targeted mainly white, vulnerable girls.
Her report described the abuse as 'appalling' and said girls as young as 11 had been raped.
She found evidence of children being trafficked to other towns and cities, abducted, beaten, intimidated and abused by large numbers of offenders.
Her report found 'blatant' failures of those in authority at the time.
Since the NCA was brought in to oversee investigations into the historic offences 38 suspects have been arrested, 18 have been charged and three have been convicted
Officers are engaging with 253 victims and there are currently 34 live investigations underway.
An NCA spokeswoman said: "The NCA is focusing on investigating information provided by victims and witnesses and identifying individual suspects or groups.
"We have hundreds of potential suspects and the priority is to support victims and survivors and identifying and investigating individuals and groups who have harmed children
"Operation Stovewood’s remit is non-familial child sexual exploitation and abuse between 1997-2013. In conjunction with partners, we are investigating allegations of child sexual exploitation and associated risks.
"This is a challenging and complex investigation, with victims and survivors re-living abuse that took place many years ago. Our focus will always be the wellbeing of the victims and we are working together to ensure the individual needs of them and their families are at the forefront of all we do
"Work to identify all potential victims of non-familial CSE in Rotherham is ongoing. We believe that Alexis Jay’s conservative estimate of 1,400 victims is a very good assessment, however, no-one will know the actual number until the enquiries are complete."
South Yorkshire's Police and Crime Commissioner, Dr Alan Billings, said he is in contact with the Home Office over the cost of the operation and he will be submitting applications for financial assistance.
He said Stovewood is the 'biggest investigation of its kind in the country'.
"As far as 2017-18 is concerned, we will not be in a position to apply for grants for the costs of Operation Stovewood until we know the full year costs, but we are in conversation with the Home Office, so they know that applications for grant will be coming," he said,.
"The National Crime Agency has asked the Home Office for additional investigators and detectives and their request has been assessed by Her Majesty's Inspectorate of Constabularies.
"We wait to see whether the Government will agree to the request. The current costs are £6.9 million per annum so these costs may rise substantially. If Special Grant is awarded, South Yorkshire Police have to stand the first 15 per cent of any costs."