The company, which declined comment on Friday, must raise between 7 billion and 8 billion euros a year through 2015 to cope with maturing debt and risks rising refinancing costs if Spain, which is debating applying for European aid, loses its investment grade rating.

While liquidity needs have eased slightly since it successfully tapped bond markets last week and signed a 1.2 billion euro credit line with Chinese banks, Telefonica is still struggling with sinking revenue and profits in its home market and a 57 billion-euro debt pile.

The head of the former monopoly's Spanish business, Luis Miguel Gilperez, warned on Friday there was still no visibility on a recovery in revenues in a "complicated" domestic market.

"We continue to believe that Telefonica has adequate liquidity even if its investment grade credit rating is lost. However, we expect negative earnings momentum to refocus investor attention on weak fundamentals," Goldman Sachs said in a recent research note.

The initial public offering (IPO) in Germany is set to take place later this year, though the exact timing will likely depend on market conditions.

Telefonica's O2 is the smallest operator in Germany after Deutsche Telekom, Vodafone and E-Plus