Cuba's power grid has collapsed again amid an energy crisis that has been worsened by a US oil blockade.Millions of Cubans were plunged into darkness once again on Saturday as the island's national electric grid collapsed for a second time in less than a week and for a third time this month. The nationwide power outage hit Cuba's communist government struggles with a run-down infrastructure and a US-imposed oil blockade. "At 18:32 (2232 UTC), a total disconnection of the National Electric Power System occurred. We will continue to provide updates," Union Electrica, the state-owned electricity entity, said in a statement on social media. Cuba's deepening energy crisis Power outages — both nationwide and regional — have become the norm in Cuba over the last two years due to breakdowns in the ageing electricity generation system. The breakdowns are aggravated by daily blackouts of up to 20 hours in parts of the island, which lacks the fuel needed to generate power. Cuba produces just 40% of the fuel it needs to power its economy. Cuba's economic crisis has worsened since January 3 as US President Donald Trump has maintained a de facto oil blockade on the Caribbean island after Washington deposed Venezuelan President Nicolas Maduro — Cuba's top ally and main energy provider. Trump threatens 'friendly takeover' Trump has not only severed Venezuelan exports to Cuba but has also threatened other nations with punitive tariffs if they sell oil to Havana. No oil has been imported to Cuba since January 9, hitting the power sector and the crucial tourism sector as airlines are forced to curtail flights. Cuba blames the US trade embargo for the country's economic failures — including its collapsing power grid — while the US says the failures are caused by Cuba's Soviet-style command economy. The Trump administration in Washington demands that Cuba release political prisoners and move toward political and economic liberalization in exchange for a lifting of sanctions. Trump has made no secret of his desire for regime change in Cuba, and has also raised the possibility of a "friendly takeover" of the island. Edited by: Karl Sexton