Citgo Petroleum holds three refineries, worth more than $10bn at Lemont, Illinois; Lake Charles, Louisiana and Corpus Christi, Texas, US.
Reuters cited Ramirez as saying during a 100th anniversary celebration of Venezuela’s oil production that: "As soon as we receive a proposal that serves our interests, we will exit Citgo.
"This is not something simple like deciding to take off a jacket, this is an issue that we’re working on."
The three refineries have a combined capacity of approximatly 750,000 barrels per day.
According to the BP Statistical Review of World Energy, Venezuela biggest oil exporter in Latin America, sending abroad 1.8 million barrels a day in 2013.
