Police are set to bring in private companies to investigate crimes and patrol neighbourhoods, it has been was reported.
Two forces, West Midlands and Surrey, are asking security firms to bid for contracts, worth £1.5bn over seven years, to run some services that are currently carried out by officers, according to the Guardian.
Successful firms would have a wide range of responsibilities, including detaining suspects and responding to incidents, but would not be able to arrest suspects.
In a briefing note sent to companies, which was seen by the newspaper, all services that "can be legally delegated to the private sector" are potentially up for contract.
Administrative roles, such as legal services and managing forensics, are also set to be outsourced.
The move will spark fears about privatisation within the police force. Ben Priestley, Unison's national officer for police and justice, told the Guardian: "Bringing the private sector into policing is a dangerous experiment with local safety and taxpayers' money
"We are urging police authorities not to fall into the trap of thinking the private sector is the answer to the coalition's cuts. The fact that the Home Office is refusing to publish its business case - even under FOI (Freedom of Information Act) - speaks for itself.
"Privatisation means that the police will be less accountable to the public. And people will no longer be able to go to the Independent Police Complaints Commission if they have a problem. When a critical incident happens, a force's ability to respond will be severely compromised. The only winners are private companies and shareholders who make profits at the expense of local services."
Simon Reed, vice-chairman of the Police Federation of England and Wales said that opening the doors for private business was "a dangerous road to take."
"The priority of private companies within policing will be profit and not people, and we must not forget, they are answerable to their shareholders and not to to the public we serve.
"This plan suggests that core policing roles such as police patrols and the power to detain, thus depriving people of their liberty, will be undertaken by private business employees."
However a Home Office spokesman said: "Private companies will not be able to arrest suspects, and they will not be solely responsible for investigating crime. Many forces already use the private sector to run custody suites so that officers can be deployed elsewhere. "
The West Midlands police authority spokesman has suggested that the new plans are part of a range of measures to "transform the way the force does business."
Chief Supt Phil Kay, who is overseeing the project, said: "This is about how we deal with the challenging conditions that we face and how we look to innovative ways to try and continue improving on delivering the service that we provide to communities.
"We want to explore how working with people in the private sector might be able to give us a new dimension and help us transform our service.
"We also want to see what areas of business there are where we can work with partners in the private sector to deliver in a way that is more cost-effective, efficient and helps to improve the service."
Mr Kay added the move was about "protecting the front line", but that they were at a very early stage of the process.
He told BBC Radio 4's Today programme: "There are some elements of investigation that it would be appropriate, or might be appropriate, for private companies to get involved with.
"But when it comes to arresting suspects, when it comes to executing power of arrest and using force both authorities and chief constables are really clear that that will continue to be done by sworn officers.
Yvette Cooper, shadow home secretary has raised worries that the new plans are a direct result of increased pressure from the government. She said: "We have not yet seen the detailed proposals for the West Midlands and Surrey Police, and we will scrutinise them in detail.
"The police have today confirmed that they are pursuing these contracts as a result of the financial pressures they face.
Yet the possibility of including the management of high-risk individuals, patrolling public places or pursuing criminal investigations in large private-sector contracts rather than core professional policing raises very serious concerns.
"It is fundamental to British policing that it has the trust of the people. That means policing decisions are impartial, in the interests of justice, stopping crime and catching criminals."