Vodafone has sold its 25 per cent stake in Swisscom Mobile for £1.8 billion (€2.6 billion) to the Swiss group's largest shareholder, as the world's biggest mobile operator continued to reduce its presence in tough markets.

The sale yesterday will generate a financial gain of just £100 million for Vodafone, which acquired the holding in January 2001. Proceeds from the sale will be used to pay down Vodafone's debt.

The deal is the latest in a series of sales that has seen Vodafone reduce its holdings in established mobile operators to focus on emerging markets where mobile phone ownership is at lower levels.

In March, Vodafone completed the £8.9 billion sale of its Japanese mobile unit to Softbank, the mobile telecoms and internet group. Last month it sold a 25 per cent stake in Proximus, the Belgian mobile operator, to Belgacom for € 1 billion. It sold Vodafone Sweden to Telenor.

At the same time, Vodafone has been active in acquiring a growing presence in emerging markets.

Last year it paid £820 million for a 10 per cent stake in Bharti, India's fastest growing mobile operator. It is also expanding in South Africa and Egypt.

Arun Sarin, Vodafone chief executive, said: "We do not see ourselves as the most appropriate holder of this minority stake in the longer term and Swisscom is keen to increase its holding in Swisscom Mobile to drive through synergies in its fixed and mobile businesses."

Swisscom's move will be welcomed by investors, who have long argued the debt-free telecoms group should leverage its balance sheet to finance growth.

Carsten Schloter, chief executive of Swisscom, said buying back Vodafone's stake in Swisscom Mobile would release an additional SFr180 million (€112 million) a year in dividends for shareholders and boost earnings per share by 10 per cent.

The money stems from the difference between the roughly SFr300 million paid annually to Vodafone in dividends on its Swisscom Mobile stake and the lower interest costs of the money Swisscom will borrow to finance the deal.