Argentine President Cristina Kirchner announced the nationalisation of Federal Petroleum Deposits (YPF), the country's largest oil extractor and refiner, on April 16.
Altogether, 51% of Spanish oil multinational Repsol's 57% stake in YPF has been claimed by the Argentine government.
The move shook the markets, with YPF shares falling 30% on the New York stock exchange.
The nationalisation has drawn condemnation from Spain, the European Union and the United States ― as well as US regional allies Chile, Colombia and Mexico. In contrast, it was applauded by Venezuela and Bolivia.