Missouri's attorney general is taking Walgreen Co. back to court, alleging the nation's biggest pharmacy chain is violating a settlement reached last year over its pricing practices.

Attorney General Chris Koster planned to announce details Tuesday in St. Louis.

Koster sued the Chicago-based retailer in 2013, accusing it of overcharging customers and using deceptive advertising and pricing schemes in Missouri.

Koster says the undercover investigation began after consumers complained that display prices didn't match up with what they paid at checkout.

The company reached a settlement in June 2014 that included having an independent auditor monitor its Missouri stores for three years.

But Koster alleges Walgreen has committed more than 1,000 violations of that settlement.

Company spokesman Phil Caruso said Tuesday he wasn't immediately familiar with any new legal action.

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