Britain’s Vodafone said core earnings would fall in 2015 due to the investment needed in the business as it recorded impairments of £6.6 billion due to fierce competition and regulatory changes in Europe.

The world’s second-largest mobile operator has reported record falls in underlying revenue in the last 18 months, as a result of numerous European rivals, regulator-imposed price cuts and European consumers reducing the number of calls they made during the recession.

On Tuesday it wrote down the value of its assets in Germany, Spain, Portugal, Czech Republic and Romania by £6.6 billion and said core earnings in 2015 would fall due to vital spending on its network to boost speed and coverage.

After selling its US business in a $130 billion (£77.33 billion) deal, Vodafone plans to invest around £19 billion over the next two years, which includes the money assigned as part of its investment programme called Project Spring.

That will bring core earnings down to a range of £11.4 billion to £11.9 billion for 2015, from the £12.8 billion it recorded in 2014 – itself down 7.4 per cent, though results were in line with forecasts and helped by an improvement in underlying trading in the fourth quarter.

“Our operational performance has been mixed,” chief executive Vittorio Colao said.

“The Group’s emerging markets businesses have performed strongly throughout the year.

“In Europe, where we continue to face competitive, regulatory and macroeconomic pressures, we have taken steps to improve our commercial performance, particularly in Germany and Italy, and are beginning to see encouraging early signs.”