Jan 13 (Reuters) - A union benefits fund filed a class action suit Wednesday, accusing Walgreen Co and generic drug maker Par Pharmaceutical Cos Inc of overcharging for various generic drugs in a bid to boost profits.

The complaint, filed by the United Food and Commercial Workers Unions and Employers Midwest Health and Pension Fund, alleges that Walgreen, the largest U.S. drugstore chain, violated federal racketeering laws.

"Starting April 1999 through December, 2006, Par and Walgreen conspired to increase their profit through at least two schemes to illegally fill prescriptions with Par's higher-priced products rather than the specific drugs prescribed by physicians," the complaint alleged.

The drugs involved included generic versions of antidepressant drug Prozac and anti-heartburn drug Zantac, the complaint said.

Neither company could immediately be reached for comment outside U.S. business hours.

The case is In re: United Food and Commercial Workers Unions and Employers Midwest Health Benefits Fund vs. Walgreen Co., U.S. District Court for Northern District of Illinois, no. 12-CV-00204.

For United Food and Commercial Workers Unions and Employers Midwest Health Benefits Fund: Dawn Goulet of Wexler Wallace.

For Walgreen: Not immediately available.

(Reporting by Saqib Iqbal Ahmed in Bangalore)

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