CORRECTED - UPDATE 2-Lukoil talked to Caixa on Repsol stake sale-source

(Corrects second paragraph to make clear Lukoil is not state-owned)

* La Caixa talked to Lukoil on possible Repsol stake sale

* Sacyr, Lukoil decline to comment

* Spain says Repsol should stay Spanish

* Sacyr up 4.9 pct, Repsol up 1.4 pct by 1040 GMT

(Adds source confirming talks with Lukoil, background)

By Sonya Dowsett

MADRID, Nov 20 (Reuters) - Spanish bank La Caixa held talks with Russia's Lukoil (LKOH.MM) about the possible sale of its 14 percent stake in oil major Repsol, a source said on Thursday, raising the spectre of a hostile bid from the Russian firm.

Spanish radio reports said on Wednesday Lukoil had an eye to acquiring a 30 percent stake in Repsol (REP.MC). Both Spain and Repsol's chairman have stressed they would prefer Repsol to remain independent and Spanish.

La Caixa holding company Criteria Caixacorp (CRIT.MC), Repsol's second-largest shareholder, said earlier on Thursday it had held informal talks about a possible sale but had received no binding offers. It did not mention names of possible bidders.

A source familiar with the talks told Reuters on Thursday the interested party was Lukoil, adding any sale to Lukoil hinged on Repsol's biggest shareholder, Sacyr Vallehermoso (SVO.MC).

"It was Lukoil," the source said. "But Criteria is playing a secondary role, the major role is that of Sacyr."

Debt-laden builder Sacyr Vallehermoso put its 20 percent stake in Repsol on the block in September as it struggles with a plummeting property market and hefty service payments on its debts.

Hopes of a possible sale to relieve Sacyr's stretched balance sheet, propelled its shares 4.9 percent higher on Thursday to trade at 6.82 euros by 1040 GMT. Repsol was 1.43 percent higher at 14.15 euros.

Sacyr declined to comment on the latest rumours surrounding the possible sale of the stake, reiterating it continued to study a possible sale and had held talks with potential buyers.

Lukoil declined to comment. Repsol said it had not held talks with Lukoil.

Lukoil is the second Russian oil company to be linked to the Spanish oil group, after rumours about interest from Gazprom (GAZP.MM) surfaced last week, although the speculation was shot down by both Gazprom and the Spanish Prime Minister.

Spain's Industry Minister, Miguel Sebastian, said on Thursday Repsol needed to remain Spanish as it was key to the country's energy supply.

"We will do everything possible for Repsol to continue to be independent and Spanish," he said in comments on Spanish radio.

Analysts said the cards were stacked against potential foreign suitors for Repsol, given government preference for Spanish shareholders.

"Spanish government interests to have Spanish controlling shareholders could be an important hurdle for prospective bidders," said Portuguese broker BPI. (Reporting by Sonya Dowsett; Editing by Andrew Macdonald)