A fire erupted on Friday at the Nico Lopez refinery in Havana, Cuba's capital, worsening an already severe fuel crisis shaped by US sanctions. Large smoke clouds over Havana Bay alarmed residents before firefighters controlled the blaze. Cuba’s Ministry of Energy and Mines confirmed the fire started in a warehouse and was extinguished without injuries or spread to nearby areas. "The workday at the Nico Lopez Refinery continues with complete normalcy," the ministry posted on social media. The fire site was near two oil tankers in Havana’s harbor. Cuba relies on oil imports but Venezuela cut supplies after the abduction of its leader Nicolás Maduro last month. The US has tightened restrictions, allowing tariffs on countries supplying Cuba with oil. This has caused power cuts, transport shutdowns, hotel closures, and reduced working hours in public services. Hospitals and schools also face cutbacks. United Nations Secretary-General Antonio Guterres warned of a possible humanitarian “collapse” if energy needs remain unmet. Support arrived from Mexico, with two navy vessels delivering over 800 tonnes of humanitarian aid. Experts say no foreign fuel tankers have docked at Cuba for weeks. Cuba produces only a third of its fuel needs and depends on imports blocked by US threats. Deputy Foreign Minister Carlos de Cossio condemned the US for imposing "massive punishment" on the Cuban people through these sanctions. He said, "Lack of fuel harms transportation, medical services, schooling, energy, production of food, the standard of living. Massive punishment is a crime." Mexico’s President Claudia Sheinbaum criticized the US sanctions as "unfair" and called for dialogue to ease tensions between Cuba and the US.