On the heels on the announcement of a $15.1 billion Wells Fargo-Wachovia deal, Citigroup is now demanding Wells Fargo to back off, saying it has an exclusive deal to buy Wachovia's banking operations.

The head of the Federal Deposit Insurance Corporation said the organization stands behind the deal it made with Citigroup to buy part of Wachovia's operations for $2.1 billion, which was agreed in principle earlier this week.

The Citigroup-Wachovia deal was arranged by federal regulators and would have relied in part on help from the government.

The Wells Fargo acquisition does not involve any government assistance, and is still subject to Wachovia shareholder and other regulatory approvals.