Reuters could not determine which U.S. companies are shipping fuel to Cuba, but there is no sign major oil traders are involved. Seeking to avoid paralysis from the oil blockade, the government authorized private businesses to ​import ​fuel for their own use for the first time in February. A spokesperson for the company behind the ad, A Granel, said it only sells to other registered private businesses. He said private ​businesses, NGOs, and diplomatic missions can and do import fuel, mostly from the United States, but did not answer questions about the impact of U.S. policy on Cuba's black market and high prices. Private Cuban companies sign service agreements with these entities for the use of state infrastructure, with a payment of about 11 cents per liter, according ​to Diaz.