Madrid - The debt-ridden Spanish builder Sacyr Vallehermoso said Monday it is continuing to negotiate the possible sale of its 20-per-cent stake in the country's biggest oil company Repsol YPF.

Spokeswoman Ana de Pro made the comment after Sacyr announced the sale of its highway operator subsidiary Itinere to US Citigroup for 7.9 billion euros (10 billion dollars).

The sale of Itinere allows Sacyr to cut its debt by 37 per cent to 12.5 billion euros.

Sacyr has not said who it is negotiating about Repsol with, but it is widely believed to be in talks with the Russian oil giant Lukoil.

Lukoil's reported plans to take a stake of nearly 30 per cent in Repsol have sparked strong criticism from the Spanish opposition, which fears Russian influence over the strategically important energy sector. (dpa)