DEERFIELD, Ill. — Drugstore chain Walgreen Co. said yesterday its $2.8 billion bid for Longs Drug Stores Corp. is superior to a competing offer from CVS Caremark Corp. and it is prepared to take it directly to shareholders if Longs refuses to negotiate a deal.

In a letter sent to Longs board members, Walgreen Chief Executive Jeffrey Rein moved to assure executives of the California-based chain that his company's $75 per share cash offer would likely face few regulatory hurdles.

He also reiterated his request for Longs to allow Walgreen to complete a due diligence review of the company's financials, a request that so far has been rebuffed at least twice.

"Our proposal is compelling — it would deliver superior value to Longs stockholders relative to the CVS transaction and can be consummated without undue delay," Rein wrote to Longs in a letter dated yesterday.

"Although we would unquestionably prefer to work directly with you to complete a negotiated transaction, we are prepared to take our transaction directly to your stockholders," he added.

Longs, based in Walnut Creek, Calif., has more than 500 stores, mostly in California, but also in Hawai'i, Nevada and Arizona. The company also owns Rx America, a prescription benefits management program with more than 8 million members.

CVS' $71.50-per-share offer, announced in August, is equivalent to about $2.7 billion. In recent weeks, several major shareholders in Longs had said CVS was undervaluing the company's real estate.

Both offers include the assumption of about $200 million in debt.

Walgreen shares fell $1.20, or 3.6 percent, to $31.76 in trading yesterday. Meanwhile, Longs shares fell 49 cents to $74.51. CVS dropped $1.09, or 3 percent, to $35.02.