Mobile phone giant Vodafone notched up its eighth consecutive quarter of rising sales after hitting a better-than-expected 2.2% rise in revenues.

Shares were up more than 4% after the company said its preferred measure of performance, group organic service revenue, edged up 2.2% to 12.3 billion euro (£10.3 billion) in the first quarter to June 30.

However, organic service revenue for the UK was down 3.2% over the period to 1.8 billion euro (£1.5 billion) after problems with a new billing system sparked a wave of customer complaints.

Group revenue slipped 4.5% to 13.4 billion euro (£11.3 billion) over the period, with European revenues falling 3.2% to 8.7 billion euro (£7.3 billion).

Vittorio Colao, group chief executive, said: "In Europe, our growth remains stable despite regulatory pressure on roaming revenue, with good performance in Germany, Spain and Italy while we are focused on improving our performance in the UK.

"Our growth momentum in AMAP remains strong, with excellent performance in South Africa, Turkey and Egypt and ongoing recovery in India."

The Newbury-based firm said the falling UK revenues were triggered by "operational challenges" caused by a new IT system for bills.

However, it added 26,000 new UK contract customers in the first quarter and drove down its consumer contract churn to 15.5%, compared to 18.9% in the quarter before.

Nicholas Hyett, equity analyst at Hargreaves Lansdown, said: "In the UK, Vodafone's revenues are still suffering from a change in its billing system, which gave rise to a flood of customer complaints.

"Looking forward the company is running field trials of its Vodafone TV service, as it bids to join in the quad-play race of combining TV, broadband, fixed line and mobile telephone services all in one package, from one provider."

The results come after the telecoms company warned last month that it could move its headquarters out of the UK following the Brexit vote.

The group - one of the UK's largest companies - said its decision would depend on whether Britain's negotiations to quit the European Union would restrict free ''movement of people, capital and goods".