The police watchdog is carrying out a major inquiry into allegations that officers deliberately changed witness statements and colluded in a cover-up over the disaster in 1989 in which 96 Liverpool football fans died.
The IPCC had previously confirmed that 1,444 police officers were under investigation, but giving evidence to the Home Affairs Select Committee yesterday (Tues) chief executive Jane Furniss said that was "just the start of it".
She said it was estimated that another 1,000 officers would come under the spotlight as the investigation moved forward.
As well as officers from South Yorkshire there are thought to be significant numbers from the West Midlands force, which was responsible for the initial investigation after the disaster.
In addition police officers from 18 other forces are expected to be put under the spotlight by the IPCC.
Mrs Furness also told MPs at the committee that since the IPCC had begun its investigation, it had emerged that not all the documents related to the disaster had been disclosed to the Hillsborough Independent Panel which published its damning report in September.
Mrs Furness told MPs that a significant number of people had come forward to say their statements had not been published or had been ignored.
She said: "There is new information coming to light after us announcing what we are doing."
Keith Vaz, the chairman of the committee asked if the IPCC had enough resources to carry out the huge task.
Mrs Furness said the Home Secretary Theresa May had made it clear that she was determined all the resources needed were available.
She added: "We are certainly asking for it. We are identifying what we need. There will be different resources needed at different points in the investigation."
