Repsol shareholder Spanish builder, Sacyr Vallehermoso SA, is also reported to be considering other proposals after Russia's largest independent crude producer first signaled it was interested in acquiring the Repsol stake.
In late October Sacyr, whose share price has dropped by almost 70% this year following the credit crunch, received a proposal from China's CNPC to buy a 20% stake in Repsol.
Earlier it was reported that LUKoil had applied to several Spanish banks for a 5.2 billion euro ($6.5 billion) loan to buy the Repsol stake.
LUKoil is seeking to buy around 30% in Repsol YPF, Spain's largest private oil and gas company, in a deal worth some 5.09 billion euros ($6.36 billion), with 20% held by Sacyr and 9.9% by La Caixa and Caixa Catalunya.