WASHINGTON, Jan 17 (Reuters) - The U.S. Justice

Department said on Friday it has filed a lawsuit alleging that

pharmacy chain operator Walgreens knowingly filled

millions of prescriptions that lacked a legitimate medical

purpose.

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.