The police watchdog has been given the names of more than 1,400 officers as it investigates South Yorkshire Police's role in the Hillsborough tragedy in which 96 Liverpool fans died, MPs have been told.
Home Affairs Select Committee chairman Keith Vaz said the Independent Police Complaints Commission (IPCC) received the names from the force's top officer.
Mr Vaz added: "The South Yorkshire chief constable wrote to me on Friday to say he sent a list of 1,444 names of former and serving officers of South Yorkshire to the IPCC. This is a huge number of names - more than we expected."
Ninety-six Liverpool FC fans died following the crush at Sheffield Wednesday's Hillsborough stadium in April 1989.
The "thorough and wide-ranging" IPCC probe will focus on "potential criminality and police misconduct in respect of police officers, both both serving and retired", Home Secretary Theresa May said.
She was opening a Commons debate on the Hillsborough Independent Panel's report, which last month revealed some fans could have survived if emergency services had responded sooner, and blamed police for an official cover-up designed to smear innocent supporters.
Attorney General Dominic Grieve last week asked the High Court to consider ordering fresh inquests into the 96 deaths.
Prime Minister David Cameron apologised to grieving families for the "double injustice" of their relatives dying in the disaster and their names being blackened for 23 years.
Mrs May told MPs: "After the truth must come justice and after the apology, accountability