The plan, revealed to The Times, coincides with DoCoMo’s forthcoming launch of the world’s first mobile handset with a built-in credit card chip— a device expected to wean an entire generation of Japanese teenagers on to the concept of credit at a far younger age than they would normally convert to plastic.

If the combined mobile and credit service takes off as quickly as DoCoMo hopes, the company could find itself extending a non-colateralised 300 billion yen (£1.5 billion) a month to about a fifth of its 50 million customers. At that level, it would be within the top four Japanese credit issuers and far bigger than most of Japan’s 80 regional banks.

The move exploits the growing popularity of DoCoMo’s range of “e-wallet” handsets that allow the phones to be charged-up with pre-paid cash, waved over a contactless reader and used for a range of purchases in shops and restaurants. More than 11 million customers are regular users.

Banking analysts expect the company’s decision to move from a pre-paid payment system into credit issuance for mobile phone customers to trigger a revolution among Japanese consumers. Some believe that it could double the number of credit card users nationwide within five years.

Other developments are conspiring to bring Japan, traditionally a cash-based consumer economy, more closely into line with Western levels of credit card use. Local government offices are allowing tax payments and medical insurance to be settled by credit card and hospitals are less insistent that the sick and wounded settle bills with wads of cash.

DoCoMo will play itself into the credit business in two phases, the first beginning next month. The company will begin to offer mobile phones equipped with credit card chips that are readable in dedicated machines across the country. In this first phase, the credit will be extended by existing card issuers such as Nicos and JCB.

In the second phase, later this year, DoCoMo will extend credit lines itself. Phone bills will show the amount spent on the in-phone credit card.

“The management team is robust, but credit issuance is a different industry to go into alone and it carries considerable risk,” Nathan Ramler, the Macquarie telecoms analyst, said. Other analysts praised the shift as a good strategy for a company with huge cash reserves, but little prospect for growth as a mobile operator.

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