The U.S. Securities and Exchange Commission is investigating Diebold's financial statements, delaying information their shareholders would need to make an decision, Chairman John N. Lauer said in a statement. As such, he said, "UTC's proposal is an opportunistic attempt to buy Diebold," the Akron, Ohio, Beacon Journal reported.

United Technologies Corp. announced Sunday it has offered $3 billion for Diebold, the manufacturer of voting machines and ATMs.

But Lauer also said the offer undervalued Diebold.

United Technologies first suggested a merger two years ago but was rebuffed. It extended a new offer to buy the company Friday. The offer would give stockholders a 40 percent premium over its closing price Friday of $24.12 a share.

United Technologies quickly issued a statement that it was "disappointed" by the decision.

"This transaction creates significant and immediate value for Diebold shareholders with no operational risk, while creating long-term value for U.T.C. shareholders," George David, United Technologies' chairman and chief executive, said on Sunday.