BARCELONA, July 22 (Reuters) - Cellnex plans to raise up to 4 billion euros ($4.63 billion) in new share capital to finance an expansion of its infrastructure portfolio, Europe's largest mobile phone towers operator said on Wednesday.

"The market opportunities for Cellnex continue to be massive," chief executive Tobias Martinez said on a call with analysts, saying that the increase was to fund potential mergers or acquisitions.

Chief financial officer Jose Manuel Aisa said the "capacity to do bigger deals is higher than last year" as the company has gained scale.

Such acquisitions could take the form of multi-stage operations to buy new infrastructure valued at up to 11 billion euros, the Barcelona-based company said.

Cellnex's CEO Martinez said the company was not seeking minority stakes in other groups unless there was a clear path to control. He said the goal was to consolidate its presence in the countries where it has operations already but that it was keeping an eye open on new countries, such as Poland.

Cellnex will issue 101.4 million ordinary shares with a subscription price of 39.45 euros, a nearly 30% discount to its Wednesday closing price.

At 4 billion euros, the increase is equivalent to around 18% of the company's current market value.

Cellnex on Monday raised its 2020 guidance after completing several investments and reported an increase in first-half core earnings, but said it expected net losses in the coming quarters.

The group raised 3.7 billion euros last year through two separate capital increases, which partially funded its purchase of the telecoms division of Britain's Arqiva.

Cellnex has bought tens of thousands of phone towers across Europe, controls more than 40,000 sites and is present in eight countries. It is seen as a central player in any consolidation of the European telecoms infrastructure market.

Spun off from Spanish infrastructure operator Abertis in 2015, Cellnex has expanded to reach a market capitalisation of nearly 22 billion euros and become the fifth largest company on the IBEX 35 blue-chip index. ($1 = 0.8639 euros) (Reporting by Joan Faus, additional reporting by Jesus Aguado. Editing by Jane Merriman)