Eight potential bidders, including one from India, are reportedly interested in acquiring Venezuelan national oil firm PDVSA's Citgo assets in the US.
However, it is unclear if Citgo's owner will press ahead with a sale of its US refining and marketing unit.
Investment bank Lazard, hired to carry out the sale, is still marketing Citgo Petroleum's Illinois refinery, unnamed sources told Reuters, even as Venezuela's president and finance minister have said Citgo's assets will not be disposed.
Reuters reported that teams from one Indian firm and five American firms have carried out detailed inspections of the Illinois refinery.
Potential bidders include India's Reliance Industries, alongside US-based firms PBF Energy, Tesoro, Marathon Petroleum, Valero Energy and Phillips 66.
Meanwhile, three American firms have reportedly shown deep interest in the Corpus Christi refinery. They include Chevron, Valero and Koch Industries' unit Flint Hills Resources.
Pursued by Reuters, a Citgo spokesman refused to respond when questioned about visits to the refineries made by potential buyers.
Marathon, Phillips 66, Tesoro and Valero representatives refused to discuss possible interest in Citgo's assets.
PBF and Reliance did not reply to requests seeking comment.
A Chevron spokesman refused to discuss merger and acquisition activity.
Koch representatives did not respond to messages seeking comment.
Caracas Cash Crunch
A sale could help Petroleos de Venezuela SA (PDVSA) rake in about $10bn (€8.1bn, £6.3bn).
The core of Citgo's US assets are three refineries in Illinois, Louisiana and Texas with a combined capacity of 749,000 barrels per day (bpd).
Analysts have said that Venezuela wants to dispose of Citgo in part due to a cash crunch, triggered after Caracas repaid debts to Beijing with oil instead of selling crude to generate revenue, analysts have said.
Caracas has, however, denied that a cashflow problem exists.