Vodafone will announce tomorrow that it is to take a hit of as much as £25bn to cover the disaster of having paid over-the-odds for acquisitions made during the telecoms boom.

At £25bn the loss would be the largest ever announced by a British company.

But analysts are predicting that the operator will take a softer option by announcing impairment charges of £7bn-£8bn for the year to reflect the fall in the value of businesses such as Mannesmann in Germany.

A spokesperson for Vodafone said the company could not make any comment on the reports ahead of the release of the results tomorrow.

Investor hopes that Vodafone could buy back shares appeared to be dashed after the operator paid £515m two weeks ago to increase its stake in China Mobile from 2.2 to 3.3 per cent.

But it is not all doom and gloom for the world's largest mobile phone company, as it is also expected to report a 34-per-cent growth in proportionate revenues, to around £29.8bn.

This is due to its expanding customer base which reached beyond 100 million for the year to 31 March.

Despite the increasing subscriber base, however, Vodafone's market value has been halved this year.

Shares fell to a record low of 92.5p at the start of this month, a long way from the heady heights of 399p in March 2000. But the share price has been rising this morning on expectations of the release of its results tomorrow.