Cuba’s national power grid collapsed on Friday, marking the second nationwide blackout this week and the fourth major outage this year, according to Reuters.

Energy Minister Vicente de la O Levy said authorities were working to restore the National Electric Power System, a complex ‌situation amid all the difficulties we face on a daily basis. The latest collapse came as part of the country, including Santiago de Cuba, were still disconnected due to severe fuel shortages following Monday’s nationwide blackout, which affected the island’s around 10 million residents. Most electricity services had been restored by Tuesday.

The repeated blackouts have been attributed to a combination of aging power infrastructure and severe fuel shortages. The outages have intensified public frustration, prompting scattered protests in Havana after Monday’s blackout.

The energy crisis has also reignited political tensions between Cuba and the US. Havana maintains that decades of US sanctions and trade restrictions have limited fuel supplies and hindered investment in the country’s power sector. Washington, meanwhile, attributes the crisis to economic mismanagement by Cuba’s government.

Cuba’s minister of foreign affairs, Bruno Rodríguez Parrilla, criticized the US measures in remarks to the UN, saying the fuel embargo and economic sanctions amounted to a “systematic violation of the human rights ⁠of an entire ​people in an act of collective punishment.”

After Friday’s blackout, he posted on social media: “It ​has been another very difficult week under the impact of the energy blockade: two nationwide grid collapses, almost no fuel to power the generating plants, and several units out of service.”