Vodafone has confirmed that current chief executive, Arun Sarin, is to stand down in July after five years at the helm.

The surprise announcement comes as the mobile operator unveiled a solid set of financial results. Sarin will be replaced by deputy chief executive Vittorio Colao.

Sarin has won widespread praise for his stewardship of Vodafone. When he took over from previous chief executive Sir Christopher Gent in July 2003, the company was facing the prospect of slow growth in its core European markets and was struggling to justify its £6 billion investment in 3G mobile licences.

"Arun has done a tremendous job as chief executive. He has led the company with distinction and navigated Vodafone through a period of rapid change," said Sir John Bond, Vodafone chairman, in a statement.

Despite the praise Sarin has garnered for growing Vodafone's customer base, from 120 million to 260 million, and pushing into fast-growing markets such as India, Czech Republic, and Turkey, Vodafone has only made slow progress on 3G during his tenure.

Currently, out of Vodafone's existing 110 million subscribers, only around 24 million are using 3G. Many of those will be using data cards and USB modems.

During its latest financial year, Vodafone recorded revenues of £35.5bn, up 14 per cent year-on-year; net profits for the year were £6.8bn up from a loss of £4.8bn the year before.