PARIS, Jan 25 (Reuters) - French media conglomerate Vivendi said on Monday it had raised its stake in Spanish rival Prisa, the owner of Spain's influential El Pais newspaper and other media assets, to 9.9% from 7.6%.

On Friday, Vivendi had announced it had bought the 7.6% stake, saying the move responded to the group's strategy to become "a global leader in content, media and communications" and to extend its reach in the Spanish-language markets in Europe, Latin America and United States.

Vivendi said it bought the stake hours after HSBC had agreed to sell a 7.89% stake in Prisa for 52 million euros ($63.3 million).

Prisa, which is struggling with a huge debt pile, is controlled by activist fund Amber Capital which is led by French investor Joseph Oughourlian.

($1 = 0.8214 euros) (Reporting by Sudip Kar-Gupta and Inti Landauro; Editing by Raissa Kasolowsky and Edmund Blair)