MADRID - State-controlled oil company Saudi Aramco is interested in buying a minority stake in the renewable unit of Spanish oil company Repsol, newspaper Expansion reported on Friday, citing unidentified market sources.

Saudi Aramco has approached Repsol as it is mostly interested in the Spanish company's renewable assets in the U.S. The Saudi giant had not filed a formal offer yet, Expansion said.

Repsol has started talks to sell a stake in its renewable energy business after receiving an unsolicited approach by an investor and has lined up Santander as advisor for the sale, four sources told Reuters earlier this month.

The Spanish company is eager to sell a stake in its renewable unit to raise cash to partly fund its strategic plan through 2027.

Two years ago, Repsol sold a 25% in the business to a unit of French bank Credit Agricole and Swiss asset manager Energy Infrastructure Partners for 905 million euros ($978.31 million).

Saudi Aramco and Repsol did not immediately respond to requests for comment.

($1 = 0.9251 euros)

(Reporting by Inti Landauro; editing by David Evans)