The government is to radically reduce the number of police forces in England and Wales as part of what sources have called the largest reform of policing in decades.

Home Secretary Shabana Mahmood will announce plans for police reform next week.

She will pledge to “significantly” cut the number of forces from its current level of 43, and tell them to focus on serious and organised crime. Police chiefs have been calling for the creation of 12 “mega forces” to save money and boost crime-fighting efforts.

It could be years before changes are implemented, with government sources saying only that it will happen by the end of the next parliament, around 2034.

Mahmood will argue in a policy proposal that the current model of 43 forces is bureaucratic and wastes money, with each force running their own headquarters, management teams and backroom staff.

Ministers also believe the performance of local forces varies too widely across England. They believe smaller forces are less well equipped to deal with serious crime and respond to major incidents.

Mahmood is expected to say new, larger forces should focus on tackling serious and organised crime, as well as complex cases like murder and drugs.

Ministers will also announce plans for new Local Policing Areas, with local officers focusing on neighbourhood policing.

It is proposed these will be set up in every borough, town or city across in England, and will be tasked with working with communities and fighting what the government calls “local crime”, such as shoplifting, phone theft and drug dealing.

Government insiders acknowledge there is an “epidemic of every day offences” going unpunished, and say they believe criminals think they can “cause havoc on our streets with impunity” because people are forced to wait hours or days for police to investigate crimes.

A government source said: “Where you live will no longer determine the outcomes you get from your force.”

Ministers will not say next week exactly how many forces will exist under the new framework. Instead, an independent review will be announced to looking at precise details.

Similar cuts have been proposed as long as 20 years ago, when then Home Secretary Charles Clarke suggested cutting the number of forces to 12.

Scotland also merged its forces in 2013 to create Police Scotland.

The home secretary’s allies will sell these reforms as part of her “modernising agenda”.

A source said: “For decades, people have called for forces to be merged. Mahmood is a politician who is not scared of bold reform and a political fight.”

Some police chiefs have called for a revamp of policing in England and have backed reducing the number of forces.

Chief Constable Gavin Stephens, chair of the National Police Chiefs’ Council, said: “Crime is changing, technology is evolving, and we need to be set up in the best possible way to tackle crime in the modern world, relentlessly focused on good quality neighbourhood policing alongside national threats.

“I know the home secretary shares this ambition. We look forward to seeing the government’s white paper and working with them to ensure policing delivers outstanding results and rebuilds confidence with the communities we serve.”

A spokesman for the Policing Federation, which represents officers from the rank of constable to chief inspector, said: “Fewer forces doesn’t guarantee more or better policing for communities.

“Skills, capabilities and equipment need significant investment if the public and officers are going to see reform deliver in the real world.

“Any proposals must be driven by evidence and best practice, not lowest cost, and must strengthen rather than weaken frontline, investigative and specialist capability, neighbourhood policing and public confidence.”