The federal Drug Enforcement Administration on Thursday asked the U.S. Justice Department's internal watchdog to investigate a whistleblower's claims that DEA agents permitted hundreds of thousands of fentanyl pills to hit the streets of New Mexico.

The request came days after an Associated Press investigation found agents repeatedly monitored - but did not seize - major shipments of the synthetic opioid in a bid to build bigger criminal cases between 2023 and 2025.

In a letter sent Thursday to the U.S. Justice Department's Inspector General, DEA administrator Terry Cole wrote that an internal probe was necessary because "the allegations have generated significant public attention and have raised questions regarding DEA's operational decisions, supervisory oversight, and response to concerns." Cole wrote in a public statement that his request "should not be interpreted as reflecting any lack of confidence in the professionalism or integrity of DEA personnel or in the investigative decisions made during this matter." "If improvements are identified, DEA will implement them," he added.