(Bloomberg) -- The US plans to hold monthly tenders to buy oil for its strategic petroleum reserve through at least May as the Biden administration moves ahead with plans to refill the caverns that currently sit near the lowest levels in 40 years. 

The energy department on Friday issued a solicitation to buy as much as 3 million barrels of sour oil for delivery in March, according to a statement. That comes on top of a previous tender to buy the same amount for February. 

The government has so far bought close to 9 million barrels of oil at an average price of $75 per barrel and secured nearly 4 million barrels in accelerated exchange returns. The efforts to refill come after the historic release of 180 million barrels in the wake of the Russian invasion of Ukraine. The US has bought oil from companies including Exxon Mobil Corp, Phillips 66 and Macquarie Group Ltd. 

Read more: US Oil Reserve’s Limits Slow Push to Refill at Low Prices

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