Vodafone has reported 2014 results in line with forecasts, helped by an improvement in underlying trading in the fourth quarter.

However the world's second-largest mobile operator warned its core earnings would fall in 2015 due to the investment needed in the business.

Vodafone has reported record falls in underlying revenue in the last 18 months, due to fierce competition in Europe, regulator-imposed price cuts and European consumers reducing the number of calls they made during the recession.

It is now investing to improve network speed and coverage after selling its stake in US joint venture Verizon Wireless. 

This sale boosted Vodafone’s annual net profit to £59.25bn, the British mobile phone giant said.

Its organic service revenue - stripping out items such as handset sales, currency movements and acquisitions - was down 3.8% in the three months to the end of March.

That was an improvement on the 4.8% drop recorded in the third quarter and the 4.9% fall in the second.