Vodafone's underlying profits for the last six months have jumped to £1.8 billion.

Meanwhile, the mobile phone giant's customer numbers around the world have risen to 65.5 million.

The group, which earlier this year triumphed in its long-fought bid for Germany's Mannesmann, said its figures showed "strong increases in profitability in all its operating regions".

Profits for the half year to September 30, stripping out one-off costs related to acquisitions, rose by 107 per cent, from £879 million to £1.8 billion.

Vodafone said its debts stood at £13.2 billion, 8.5 per cent of the group's market value on the stock exchange, which takes into account paying out for third-generation mobile phone licences in the UK, The Netherlands and Germany.

In the UK, customer numbers rose to 10.2million, the group said.

Vodafone said it had made "good progress" in integrating Mannesmann into the group after completing the acquisition on April 12.

That deal in turn led to Vodafone's sale of Orange, which it acquired as part of the Mannesmann deal, to France Telecom.

Since the end of the half-year, other deals have included Vodafone taking a two per cent stake of China Mobile for £1.7 billion, while it has also agreed to take a 25 per cent interest in Swisscom Mobile for £1.8 billion.

Chief executive Chris Gent said he was still keen to expand the group further and Vodafone was looking at more opportunities around the world.

With the majority of third-generation licences now purchased, and the group's disposal programme largely complete, Vodafone's balance sheet would allow it to continue to "take advantage of opportunities to expand strategically and geographically as they arise".