Mobile phone giant Vodafone is set to announce one of the largest write-downs in corporate history in its annual results tomorrow.

The group is also due to disappoint shareholders by pulling plans for a share buyback and resisting calls for a healthy increase in the dividend.

Vodafone could write-down as much as £15 billion after the value of its overseas acquisitions fell in the wake of the telecoms slump.

Chief executive Sir Chris Gent will focus on the underlying performance of the business but the write-downs will reflect the sharp downturn in the sector.

The value of telecom shares has plunged on fears about subscriber growth and doubts whether the investment in third generation (3G) mobile phone licences would pay off.

Vodafone fell below the 100p barrier on the stock market earlier this month to less than a quarter of the 399p high reached in March 2000.

The write-downs will push Vodafone into a huge loss for its most recent financial year to the end of March.

At the half-year stage, the group cut £4.5 billion from the value of recent acquisitions, including its Arcor fixed-line business in Germany.

Analysts believe this week could see Vodafone reassess the carrying value of its stakes in China Mobile and its fixed-line operations in France.

Vodafone is likely to admit the assets no longer reflect the prices it paid at the height of the telecoms boom.

Shareholders had been hoping for a buyback of around £3 billion to shore up the share price but this was likely to be rejected at a board meeting today.

The telecoms giant's decision to keep hold of the cash could fuel fears it is on the verge of further acquisitions.

Vodafone splashed out £75 billion on German firm Mannesmann, £42.5 billion on US group AirTouch and bought a host of smaller companies in the late Nineties, in a spending spree which dramatically transformed the group.