The Post Office is drawing up plans to close dozens of branches and axe hundreds of head office jobs as it tries to place its finances on a sustainable long-term footing.
Sky News has learnt that the state-owned company is preparing to announce in the coming days that it will shut or seek alternative franchising arrangements for more than 100 wholly owned branches.
The affected branches collectively employ close to 1,000 people and are said to be significantly loss-making.
A significant number of jobs - believed to be in excess of 1,000 - are also understood to be at risk at the Post Office's headquarters. Further details of where the axe would fall were unclear on Tuesday afternoon.
Whitehall insiders said that the government had been consulted on the plans, which come as ministers explore the possibility of handing ownership of the network to thousands of sub-postmasters across Britain.
They added that union officials had also been briefed on the proposals, with one suggesting that an announcement could come as early as Wednesday or Thursday.
The cost-cutting measures are said to be designed to help the Post Office stem substantial financial losses, with the company requiring an annual government subsidy to stay afloat.
One government source said the plans should be seen in the context of comments made by Jonathan Reynolds, the business secretary, on Monday at the public inquiry into the Horizon IT scandal.
Giving evidence, Mr Reynolds said: "I think despite the scale of this scandal, the Post Office is still an incredibly important institution in national life.
"I look at the business model of the Post Office, and I think even accounting for the changes in the core services that are provided ... there's still a whole range of services that are really important.
"But I don't think postmasters make sufficient remuneration from what the public want from the Post Office, and I think that's going to require some very significant changes to the overall business model of the Post Office."
Improvements to the pay and working practices of sub-postmasters are expected to be announced imminently, the government source added.
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The 364 year-old institution has been engulfed in crisis since the scale of the Horizon scandal became clear, with hundreds of sub-postmasters wrongly prosecuted for theft and fraud offences.
Brought to a wider public audience by the ITV drama 'Mr Bates vs The Post Office', it has been labelled Britain's biggest miscarriage of justice.
Many of those affected suffered ill health, marital breakdowns or died before they were exonerated.
Former chief executive Paula Vennells, who insisted for years that the Horizon system was robust, was effectively stripped of her damehood in disgrace earlier this year.
Last month, Sky News revealed that the Department for Business and Trade (DBT) has asked BCG, the management consultancy, to examine options for mutualising the Post Office.
BCG's work is expected to include assessing the viability of turning the Post Office into an employee-owned mutual, a model which is used by the John Lewis Partnership.
The Post Office is Britain's biggest retail network, with roughly 11,500 branches, with the public's shareholding managed by UK Government Investments (UKGI).
In recent months, calls for a review of the company's ownership model have grown amid a corporate governance fiasco at the company.
In January, Henry Staunton, the chairman, was sacked by Kemi Badenoch, the then business secretary.
Mr Staunton subsequently disclosed an investigation into bullying claims against Nick Read, the Post Office's chief executive, which the organisation said in April had exonerated him.
Mr Read, who has since resigned, was accused of constant attempts to secure pay rises, even as sub-postmasters were facing protracted delays to their entitlement to compensation after being wrongfully convicted.
As part of their efforts to repair the Post Office's battered finances and reputation, the government has parachuted in Nigel Railton, a former boss of National Lottery operator Camelot, as its chairman.
The Post Office has been contacted for comment.