Royal Mail is selling off post office premises worth £20 million as part of its closure programme.

A total of 40 post offices, mainly large high-street branches in medium-sized market towns, are up for sale. They are all part of the Crown Post Office network which is directly managed by Royal Mail.

The news follows last week’s back-bench rebellion in the House of Commons when 20 Labour MPs voted to call a halt to the Government’s plans for closing 2,500 loss-making post office branches.

A spokeswoman for the Post Office said of the 40 properties being sold: “These buildings became vacant because last year we announced a deal with WH Smith which was about relocating some of our Crown office branches into their stores. That has been happening over the past year. The Crown office part of the network has been losing £70 million a year and was not sustainable. As we would do with any surplus buildings, we are looking to sell them.”

The Post Office will continue to run 373 Crown post offices alongside branches run by private sub-postmasters and by retailers. By the end of summer 2008 it is expected that 76 Post Office branches will be sited within WH Smith stores.

Alan Duncan, Shadow Business Secretary, said: “Royal Mail can manage their property portfolios as they choose, but this should not be a surrogate means of extra post office closures.”

The post office branches for sale include ones in Aberdeen, Aylesbury, Brighton, Cheltenham, Hull, London, Newcastle-upon-Tyne and Torquay.

It is understood that Royal Mail has already received a lot of interest in the buildings, mainly from local businesses. Although they have only just been put up for sale, it is thought that many will be turned into restaurants, bars and shops.

Anyone wishing to buy the former post office buildings must apply for planning permission to convert the properties. Half of the premises are leasehold and half are freehold.

Atisreal UK, a commercial real estate company, confirmed that it was marketing a number of properties for Royal Mail but would not comment on the particulars of the arrangement.

At the moment there are more than 14,000 post offices in Britain, down from the 25,000 open in the 1960s. The axe began to fall in the 1970s when the Conservative Government closed 3,500.

Since it came to power in 1997, Labour has shut another 4,000. If the party goes ahead with the proposed 2,500 closures, this will significantly reduce the size of the network.

The number of visits made to post offices has been falling in recent years. TV and driving licences, car tax and passports can be bought online or through other outlets. Bills can be paid on the internet and the proliferation of direct debits, cash machines and internet banking have impacted on the profitability of post office branches.

In addition, much mail is sent via a Post Office competitor and changes to the benefits system mean that payments go directly in bank accounts.

The Post Office said that employees at the 40 defunct Crown office branches were offered the option to transfer to WH Smith or another part of the network or offered redundancy.

Times Recommends

• Minister in talks with Saudis to protect creditors
• Premier Inn hits back in £29-a-room row
• Bankers hit back at 'populist' bonus supertax