The Post Office already sells mortgages online and over the phone but hopes that by bringing in specialists to its huge branch network it can offer a "genuine alternative" to the banks.

Specialists are being introduced in five large branches in Birmingham, Solihull, Walsall, Luton and Norwich this week ahead of a wider roll out to hundreds of sites.

The Post Office's new mortgage software will enable customers to find out how much they could borrow and view product features and repayments on screen. Within a few minutes they can get a printed Approval in Principle or have the opportunity to submit a full application.

Mike Cook, head, mortgages, Post Office, says: "By introducing Mortgage Specialists in our branches, we are taking the next step in fulfilling our ambition to become one of the best providers in the market place and to be a genuine alternative to the established high street providers."

The Post Office is just one of many outsiders seeking to compete with unpopular UK banks. Earlier this week, Tesco began offering home loans, while fellow retail giant Marks & Spencer is also offering banking services.