The U.S. Justice Department is accusing Walgreens of filling millions of prescriptions in the last decade and more without a legitimate purpose, including for dangerous amounts of opioids, according to a lawsuit filed this week.

If found liable, Walgreens, which is one of the country's largest pharmacy chains with over 8,000 pharmacies across the U.S., could face civil penalties of up to $80,850 for each unlawful prescription, the Justice Department said in a statement.

The U.S. Justice Department on Friday accused pharmacy chain operator Walgreens Boots Alliance of contributing to the U.S. opioid epidemic by filling millions of unlawful prescriptions for addictive painkillers and other drugs.