US President Donald Trump has announced what he described as the “biggest oil deal in world history”, giving US companies majority control over more than 65 billion barrels of Venezuela’s proven oil reserves.

Trump said the agreement, reached with Venezuelan interim President Delcy Rodriguez, would more than double US oil reserves and help lower fuel prices for American consumers. He said the deal would come at no cost to US taxpayers.

The agreement follows weeks of negotiations aimed at giving American companies long-term access to Venezuelan oilfields while securing crude supplies for US refineries. Venezuelan officials are expected to sign new oil exploration and production agreements with several companies next week.

Venezuela holds the world’s largest proven oil reserves but currently produces about 1.25 million barrels per day, well below its potential due to years of underinvestment, mismanagement and sanctions. The deal is expected to bring significant investment to the country’s struggling energy sector.

Trump did not provide details on the structure of the agreement, the oilfields or the companies involved. US Secretary of State Marco Rubio said the deal would provide stable, low-cost oil to the US, while bringing nearly $100 billion in private investment and supporting Venezuela’s economic recovery.