Repsol is the top oil refinery in Spain and is among the largest private oil and gas companies in the world. The acquisition gives Russia a foothold in Europe as diplomats from both sides raise the regional energy market as a geopolitical concern.
Russian gas monopoly Gazprom would purchase the 20-percent stake from the Spanish construction group Sacyr Vallehermoso, which is facing a looming fiscal crisis as several of its past acquisitions were financed by nearly $6.5 billion worth of debt.
Debt-backed financing turned sour when credit markets froze in October, leaving Sacyr in a position to seek assets to meet its outstanding loan obligations, the Financial Times said Friday.
Madrid is divided over the deal, however, with energy officials warming to the deal, while Prime Minister Jose Luis Rodriguez-Zapatero opposed the move in favor of international options.
A Gazprom spokesman denied the allegations to RIA Novosti Friday, however. "All talk of this is based on the fact that they want to sell this stake -- but that does not mean anyone wants to buy it," said Gazprom spokesman Sergei Kupriyanov.
The news of the possible acquisition comes as the European Union releases an energy-diversity plan meant to ease its dependency on Russian natural resources.