By Andrés González and Isla Binnie

The Spanish company has been buying up phone tower sites across Europe, riding a wave of debt-cutting efforts by telecoms network operators which are selling or sharing their infrastructure to maximise profit.

In the first half, during which it inked a blockbuster $3-billion deal to buy masts from French tycoon Xavier Niel, Cellnex made 321 million euros ( £287 million) in core earnings before interest, tax, depreciation and amortisation.

That was an increase of just over 10% on the same period last year and fell exactly in line with a forecast provided by the company, based on estimates from 31 analysts.

The results set Cellnex up to reach the upper limit of its targeted 640-655 million euros in core earnings for the full year, Chief Financial Officer Jose Manuel Aisa told Reuters.

"We are very much in line, in the higher part," Aisa said, adding he expected to rake in 647-655 million euros.

Aisa said the company was seeking more acquisitions to add to a portfolio which, once the deal with Niel's firms is finalised, will contain more than 45,000 sites across Spain, France, Netherlands, Britain, Italy and Switzerland.

Ninety percent of the company's focus is on Western Europe, Aisa said.

Communications masts have long been a popular investment target for private equity firms because of their steady cash flows.

With around 350,000 such towers in Europe, Aisa said, there are opportunities for many other companies to pile in, especially as the roll-out of next generation 5G networks requires more such infrastructure.

The sector "is still in its infancy, these are just the first shoots," he said.

(Reporting by Andrés González and Isla Binnie; Editing by Mark Potter)

By Andrés González and Isla Binnie