The acting director of the US Bureau of Alcohol, Tobacco and Firearms (ATF) and the US attorney in Arizona are resigning over a botched operation to track the flow of guns to Mexico.
The ATF’s Kenneth Melson had recently faced pressure by Congress to resign.
Operation Fast and Furious saw US agents allowing thousands of guns into Mexico illegally with the hope of tracing them to major arms dealers.
But hundreds of guns went missing and dozens have turned up at crime scenes.
The operation never led to any arrests.