Wachovia’s surprise $15.1 billion merger with Wells Fargo violates our exclusivity agreement, spurned suitor Citigroup charged just hours after the deal’s announcement Friday morning.

“Citi has demanded that Wachovia and Wells Fargo terminate and not proceed with any proposed transaction,” Citigroup said in a statement citing “substantial legal rights,” which suggested the New York bank could mount a court challenge to the rival deal. “The Exclusivity Agreement provides, among other things, that Wachovia will not enter into any transaction with any party other than Citi, and will not participate in any discussions or negotiations with any third party,” Citigroup said.

In a conference call, Wells Fargo Chief Executive John Stumpf responded: “We’re not aware of any merger agreements that had been consummated. We feel very confident that this transaction has been done appropriately. Wachovia CEO Robert Steel, however, declined to say whether the company had a binding merger agreement with Citi.

Citigroup and Wachovia, reeling from the credit crisis, announced a merger deal that was brokered by federal regulators on Monday. That $2.2 billion deal involved only Wachovia’s banking operations and excluded its asset management and other businesses.

By contrast, Mr. Stumpf said, the deal for Wachovia is a “whole company transaction. There’s nothing left behind.”

Wachovia shareholders would receive 0.1991 shares of Wells Fargo common stock for each share of Wachovia. Based on Wells’ $35.16 closing price on Thursday, the deal is valued at $7 per Wachovia share.

To finance the deal, which requires shareholder and regulatory approval, Wells Fargo plans to raise $20 billion, primarily through a stock sale. The transaction is expected to close in the fourth quarter, Mr. Stumpf said.

The combined company would have $1.42 trillion in assets and deposits of $787 billion in 10,761 branches.

The deal with San Francisco-based Wells Fargo would require not financial assistance from the Federal Deposit Insurance Corporation, the companies said.