The police watchdog is carrying out 187 investigations into possible failings by police in their handling of historical child sex abuse cases, it has been reported.
Complaints have been received by the Independent Police Complaints Commission (IPCC) about 18 forces, including allegations of what it calls "high-level corruption".
So far 27 inquiries have concluded leading to up to 15 officers facing potential disciplinary action, figures obtained by the BBC under Freedom of Information laws.
More than a quarter of the probes reportedly relate to South Yorkshire Police in its handling of child sexual exploitation in Rotherham.
Allegations made against the Metropolitan Police account for 46 of the investigations, some of which centre on allegations that investigations being halted and evidence suppressed.
They are said to include allegations that investigations ended prematurely or prosecutions were not pursued because the suspects were politicians, although these are far from being proven, the BBC said.
Meanwhile Essex Police faces 58 probes. The forces are among 17 in England and one in Wales that face investigations.
The IPCC's director of major investigations, Julian Blazeby, said: "We continue to receive referrals on police actions in child sexual abuse cases from forces across the country.
"The IPCC is committed to investigating the most sensitive and serious incidents of alleged police wrongdoing and many child sexual abuse cases fall within that remit."
The IPCC is carrying out 84 independent inquiries where it is directly involved at 18 forces, 53 of which are into South Yorkshire Police, the BBC reports.
The watchdog is handling 102 managed inquiries, in which it oversees internal police investigations, at four forces including Essex Police and the Metropolitan Police.
The IPCC is supervising one case at Norfolk Police, in which it is monitoring the internal police investigation.