India's Bharti Airtel Ltd (BRTI.NS) has agreed to sell more than 3,500 of its mobile phone masts in six African countries to telecommunications tower company Eaton Towers in a bid to cut costs, the companies said on Monday.

Bharti Airtel will lease back the towers from Eaton under a 10-year contract, the companies said in a statement. They did not disclose financial details of the deal.

In July, Bharti Airtel agreed to sell about 3,100 masts in four African countries to Helios Towers Africa. The sales are part of the Indian group's plan to divest most of its more than 15,000 towers in Africa in a process that sources have said could raise up to $2 billion.