African mobile infrastructure firm IHS Towers has secured $522 million of debt and equity to help it build more than 1,000 build-to-site towers in Nigeria, Côte d’Ivoire and Cameroon.

IHS Towers says it has 8,500 towers in its tower portfolio in Africa and that it has built over 3,000 for its clients.

The firm says it has just secured debt finance of $280 million led by the World Bank’s International Finance Corporation (IFC). Meanwhile, additional equity raised by IHS comprises of $242 million from investors.

With this latest fund raising round, Nigerian-headquartered IHS says total financing raised by the firm has topped $1 billion.

Meanwhile, IHS adds that one of Asia’s “premier sovereign wealth funds” has been added to its shareholder base. The name of the Asian sovereign wealth fund, though, has not been disclosed by IHS.

The addition of the Asian fund to its list of shareholders joins the likes of Wendel, one of Europe's leading investors, which completed an investment in IHS earlier this year.

Meanwhile, Wendel, in a statement on Wednesday, says it has also contributed to the $242 million in capital raised by IHS.

The European investment firm says it has made a complementary investment of $100 million in IHS Holding via Oranje-Nassau Développement, bringing its total investment in IHS to $276 million. With this transaction, Wendel says it is IHS's largest shareholder, holding nearly 35% of the company.

Wendel says that it along with the likes of Emerging Capital Partners, Investec Asset Management Africa and the Asian sovereign wealth fund are shareholders who have taken part in the capital increase.

And IHS says that apart from building more towers with the funding, the mobile infrastructure firm also plans to invest in solar and energy efficiency solutions, and expand to additional markets.

“Raising over $1 billion in 12 months is a clear sign of a strong business model and a vote of confidence from new and existing shareholders in the future growth of mobile telecoms in Africa,” says Issam Darwish, vice chairman and chief executive officer of IHS.

“This new financing round is critical to our aim to increase the portfolio to 20,000 towers under management, and will underpin our value creation strategy in the years to come,” Darwish adds

However, competition in the tower management and leasing business is heating up in Africa.

This week infrastructure firm Helios Towers has announced that its subsidiary has struck a transaction deal with Vodacom Tanzania in which Helios has added 1,149 mobile towers to its portfolio.

As a result, Helios says its tower coverage in Africa has reached 4,700 owned towers.

Mobile operators in Africa are also increasingly looking to rent towers or even sell their own towers to firms such as IHS in a bid to to cut their operating expenditure (OPEX).

Cutting costs is becoming increasingly key for mobile operators in Africa as the Average Revenue Per User (ARPU) on the continent has been falling over the last few years owing to lower voice costs.

Mobile operator Vodacom, for example, last week reported that in its home market South Africa its ARPU declined from R126 in June 2012 to R125 in June 2013.

“It is clear that there is no massive competitive advantage any longer in owning your own passive infrastructure, so, therefore, it makes more sense to let somebody who does that for a living do that for you,” Khumo Shuenyane, group chief strategy mergers and acquisitions officer for MTN, told ITWeb last year.