LONDON (AFP) - British mobile phone group Vodafone has chalked up a first-half loss of 5.105 billion pounds due mainly to the write-down of assets bought at the height of the telecoms bubble.

Vodafone, which has 191.6 million customers across the globe, said revenues climbed 4.1 percent to 15.594 billion pounds in the six months to September 30, boosted by the sale of the group's Swedish and Japanese operations.

The first-half loss, equivalent to 7.573 billion euros or 9.711 billion dollars, compared with a net profit of 2.775 billion pounds during the same period of the previous fiscal year, the company said in an earnings release.

Vodafone, which is struggling with intense competition in Europe, said it had taken a further impairment charge of 8.1 billion pounds, largely related to its acquisition of German telecoms group Mannesmann in 2000.

Earlier this year, Vodafone wrote off some 23.5 billion pounds to reflect its dwindling long-term growth prospects in Germany and Italy.

Meanwhile, earnings before interest, tax, depreciation and amortisation (EBITDA) rose by 2.8 percent to 6.242 billion pounds, beating analysts' consensus forecasts of 6.05 billion.

Vodafone, which retained its financial targets for the full year, saw its share price rise 0.92 percent 137.25 pence in mid-afternoon trade, as brokers welcomed the stronger-than-expected set of interim results.

London's FTSE 100 index of leading shares meanwhile slid 0.16 percent to 6,184.50 points.

"These results show that Vodafone is on track to deliver on its key targets for the current financial year," said chief executive Arun Sarin in comments accompanying the release.

"Competitive and regulatory pressures in the European region have been offset by strong performances in our developing markets and the United States."

Vodafone reported flat organic revenue growth in Europe in the first half.

Germany, Italy and Britain saw revenues fall further, but Spain continued its recent rise, posting a double-digit jump in turnover.

The performance in its emerging markets was strong enough to offset anaemic growth in western Europe.

Vodafone is targeting revenue growth in the region of 5.0-6.5 percent for the year ending March 2007.

Alongside the results, Vodafone revealed it had signed an exclusive mobile phone agreement with US Internet giant Yahoo to provide advertising services to British customers.

Vodafone had agreed last March to sell its struggling Japanese unit Vodafone K.K. to Japanese Internet group Softbank Corp for about 8.9 billion pounds.

In common with rival operators, the British group faces falling growth rates in core Western European markets, which has prompted it to invest heavily in less mature markets such as Turkey and Egypt.