Russia's second biggest oil producer OAO Lukoil (LKOH.RS) is in talks with key shareholders of Repsol YPF SA (REP) to buy a large stake in the Spanish oil company, people familiar with the situation said Thursday.

Russia's second biggest oil producer OAO Lukoil (LKOH.RS) is in talks with key shareholders of Repsol YPF SA (REP) to buy a large stake in the Spanish oil company, people familiar with the situation said Thursday.

Spain's government Thursday, however, gave mixed signals about its attitude toward a possible deal, emphasizing that the company should remain Spanish, even if Lukoil enters its shareholdings.

At Repsol's current share price of EUR13.98, a 30% stake would be worth EUR5.1 billion, but Spanish media have said Lukoil could pay as much as EUR26.6 per share.

Repsol's main shareholder Sacyr Vallehermoso SA (SYV.MC) is in talks to sell its 20% stake to Lukoil or another company. Lukoil also is in talks with Repsol's No. 2 stakeholder Criteria CaixaCorp SA (CRI.MC), the investment arm of Spanish savings bank La Caixa, the people familiar with the situation said.

Criteria has a 9.1% direct stake in Repsol, and about another 5% via the investment vehicle Repinves set up by La Caixa and savings bank Caixa Catalunya.

Repsol and Lukoil declined to comment, while Sacyr reiterated Thursday it was holding talks with several parties on a possible sale of it Repsol stake.

Criteria Thursday said it has held informal talks on a potential sale of its stake, but didn't disclose with whom, and said the talks so far had not led to any firm offers.

The talks with Lukoil are being led by Sacyr, which is facing difficulties in servicing its EUR19.39 billion in debt.

Spanish Prime Minister Jose Luis Rodriguez Zapatero Thursday didn't reject the possibility of Russia's OAO Lukoil (LKOH.RS) buying a stake in Repsol YPF SA (REP), but said it would be good if the company could nevertheless remain Spanish.

The government must respect negotiations between private companies, Zapatero said, but added that Spain's government "understands that it is good if Repsol remains" in Spanish hands.

Spanish Industry Minister Miguel Sebastian earlier Thursday had said Spain's government will do everything it can to keep Repsol "independent and in Spanish hands."

Sacyr's shares rose 9.1% to EUR7.09 at 1402 GMT Thursday, while Repsol was up 0.2% to EUR13.98.