The Drug Enforcement Administration authorized large increases in the production of painkillers even as the number of opioid-related deaths in the United States soared, the Justice Department’s inspector general said in a harsh review on Tuesday.

The watchdog office said that the D.E.A. was “slow to respond” to the opioid crisis, adding that more than 300,000 Americans have died of opioid overdoses since 2000.

“We found that the rate of opioid overdose deaths in the United States grew, on average, by 8 percent per year from 1999 through 2013 and by 71 percent per year from 2013 through 2017,” the review said. “Yet, from 2003 through 2013 D.E.A. was authorizing manufacturers to produce substantially larger amounts of opioids.”

The D.E.A., an arm of the Justice Department, is the federal agency that most directly oversees access to opioids.