Profits at NTT DoCoMo, Japan's main mobile operator, have almost vanished, as the firm suffered from its waning foreign investments.

DoCoMo posted a 95% plunge in half-year net profits, earning just 4.2bn yen (£22m; $34m) during the period, despite steady sales.

The firm, pioneer of i-mode wireles internet technology, now expects a group net profit of 182bn yen this year, only one-third of its previous forecast.

The company's fading fortunes are partly the result of a shift to US accounting standards, which have painted a far less generous picture of its fortunes.

But the firm has also been hit by weak performance overseas, and recently announced that it would be freezing its investments abroad.

Expensive publicity

DoCoMo's international strategy has largely been driven by its desire to promote i-mode as an alternative to the third-generation mobile systems currently being trialled elsewhere in the world.

I-mode, which has the advantage of considerable experience on the Japanese market, has started to catch on elsewhere, but the cost for NTT DoCoMo has been prohibitive.

The firm has invested 1.9 trillion yen to take minority stakes in several foreign carriers, including Hutchison 3G UK Holdings and AT&T Wireless Services.

But as telecoms shares have fallen, the firm has had repeatedly to write down the value of those foreign assets, including a charge of more than 900bn in the year to March.