Dozens of police officers are being investigated for using anabolic steroids supplied by criminals in gyms, a report has revealed.
It also says some officers abuse their power to obtain sexual favours.
The Association of Chief Police Officers in England and Wales ordered the report from the anti-corruption group Transparency International.
The Police Federation of England and Wales said a “very low” number of officers tested positive for drugs.
Transparency International is a non-governmental group which monitors corporate and political corruption.
Its report urges “zero tolerance” on corruption and says forces should not “fire-fight” their way from crisis to crisis.
Acpo’s spokesman on professional standards, Staffordshire Chief Constable Michael Cunningham, said the problems caused by officers taking steroids were “a significant threat” to the integrity and professionalism of the police service.
Mr Cunningham said almost all of the 43 forces in England and Wales were investigating police officers involved in bodybuilding who had formed inappropriate relationships with people supplying the drugs.
“In most forces there will be a police officer who is into bodybuilding and the gym and who would abuse steroids,” he said.
Such cases would often start with officers going to gyms, starting to experiment with steroids – “then the relationships they form when they’re using steroids become corrupt and corrosive”, he added.
George Gallimore, lead officer on drugs issues for the Police Federation of England and Wales, said: “Officers should be dealt with appropriately under misconduct regulations if they are found to be taking drugs.
“Random drug tests are already carried out and there is a very low percentage of officers who test positive.”
Nicole Sapstead is director of operations at the UK Anti-Doping organisation, which is the principal advisor to the government on drug-free sport in the UK.
She said: “As well as being performance-enhancing, steroids carry serious health risks for the individual using them, which is why they are included in the World Anti-Doping Agency’s list of prohibited substances in sport.
“We work closely with law enforcement agencies such as the police to sanction anyone committing a breach of the rules.”
Mr Cunningham said other top risk factors for corruption included the misuse of information systems.
He said most forces were also investigating allegations against officers “abusing their position for sexual favour”.
Responding to these specific claims, a Police Federation spokesman said: “We do not condone such behaviour. However, these incidents are extremely rare and there are misconduct procedures in place to cover such allegations.”
Later this week, chief constables will meet to talk about how best to tackle corruption allegations.
They will discuss plans including making gross misconduct hearings open to the public and the media as well as setting up ethics committees – independent of the police and crime commissioners – for each force.
In December, the Inspectorate of Constabulary called on forces to improve plans to combat corruption.
Investigations into corruption are rising but too few forces are gathering intelligence to prevent it happening, it found.