Justice Department sues Walmart, saying it fueled the nation’s opioid crisis.

The Justice Department sued Walmart on Tuesday for what it said was the company’s role in fueling the nation’s opioid crisis by allowing its network of pharmacies to fill millions of prescriptions for opioids, thousands of which authorities said were suspicious.

The 160-page civil complaint alleges that the retail giant knew that its system for detecting illegitimate prescriptions was inadequate and details numerous instances when Walmart’s own employees warned federal authorities and company managers about possibly suspicious prescriptions.

“As one of the largest pharmacy chains and wholesale drug distributors in the country, Walmart had the responsibility and the means to help prevent the diversion of prescription opioids,” Jeffrey Bossert Clark, acting assistant attorney general of the Justice Department’s civil division, said in a statement. “Instead, for years, it did the opposite — filling thousands of invalid prescriptions at its pharmacies and failing to report suspicious orders of opioids and other drugs placed by those pharmacies.”

In one instance, an employee identified only by his or her initials admitted to the Drug Enforcement Administration to filling prescriptions that the employee knew were not legitimate, the lawsuit alleges.

At other times, Walmart pharmacists reported to the compliance unit at the company’s headquarters in Bentonville, Ark., that they had serious concerns about various prescribers, identifying them as pill mill doctors, the suit says.

The government also said pharmacists filled prescriptions for dosage amounts so large that if the pills were taken as dispensed the patient would have likely died. Such prescriptions should have raised red flags for any pharmacist, the department claimed.

Walmart pre-emptively denied the charges in October in a suit against the Trump administration, saying that the government was using the company as a scapegoat and blaming the opioid crisis on the federal government’s own weak enforcement. Walmart did not immediately respond to a request for comment on Tuesday.

“When processes to safeguard against drug diversion are violated or ignored, or when pharmacies routinely fill illegitimate prescriptions, we will hold accountable anyone responsible, including Walmart,” Timothy Shea, the acting head of the Drug Enforcement Administration said in a statement.