The offer is part of a roughly $50bn proposal to resolve more than 2,000 suits filed by state and local governments.
The United States Justice Department sued Walmart Inc on Tuesday, accusing the retailer of fuelling the opioid crisis in the country and ignoring warning signs from its pharmacists, according to a court filing.
The retailer’s shares fell about 2 percent following the news.
The lawsuit, filed in the US district court in Delaware, alleges Walmart failed to take its gatekeeping duties as a pharmacy seriously.
Walmart, the world’s biggest retailer, created a system that turned its 5,000 in-store pharmacies into a supplier of highly-addictive painkillers, dating as early as June 2013, the lawsuit said.
The Trump administration’s allegations come months after the retailer filed a lawsuit in October against the federal government, seeking clarity on the roles and legal responsibilities of pharmacists and pharmacies in filling opioid prescriptions.
The opioid epidemic has killed roughly 450,000 people across the US since 1999 due to overdoses from prescription painkillers and illegal drugs.
Walmart was not immediately available for comment when contacted by the Reuters news agency.