Royal Bank of Scotland Group PLC has attracted at least 11 bidders for its Global Merchant Services business, valuing the unit at up to $3.8 billion, people familiar with the situation said Thursday.

Among the bidders for the credit card processing unit are several private-equity firms, including TPG Inc.; Warburg Pincus LLC; Kohlberg Kravis Roberts & Co.; and CVC Capital Partners.

Royal Bank of Scotland had set Wednesday as the deadline for bids.

Global Merchant Services, which includes the U.S. processor RBS Worldpay, appeals to buyout companies because it has a stable cash stream that private-equity owners could use to cover the interest on loans used for later acquisitions, observers said.

Chase Paymentech, a unit of JPMorgan Chase & Co.; and the technology firm Voice Commerce Group, whose chairman and chief executive is Worldpay's founder Nick Ogden, have also made bids, the people said.

Worldpay makes up the largest part of the business and has operations in more than 40 countries.

Royal Bank of Scotland, which is 84% government owned, has been ordered by the European Union to sell Global Merchant Services and other assets, after receiving the world's largest state bailout after its near collapse during the financial crisis in 2008.

Analysts say that while Royal Bank of Scotland would be better off keeping the unit, $3.8 billion would be a good price for a forced sale.

Although the bank has been given four years to make the disposals, it has been moving fast, including a sale of 318 U.K. branches, as it pushes forward with a massive restructuring plan.

Royal Bank of Scotland will narrow down the bidders for the Global Merchant Services unit to about five in the next weeks. It expects to close a deal in the second half of the year.

Royal Bank of Scotland might also agree to finance the deal by providing a loan to the buyer. In addition, the chosen buyer will also be able to decide whether the bank should keep a 20% stake in the business.

Adil Moussa, a senior analyst with the research firm Aite Group LLC, said the deal is part of a recent trend of banking companies divesting their acquiring and processing businesses, a move he views as logical.

"It's basically raising some equity and also concentrating on core business for the bank," he said.

First National Bank of Omaha recently sold a 51% stake in its merchant acquiring business to the processor Total System Services Inc. for $150.5 million.

Fifth Third Bancorp sold a 51% stake in its acquiring business for $2.35 billion last year to the private-equity firm Advent International, which has been named as a possible bidder for the RBS business.

"Processing is becoming a commodity," Moussa said. "A lot of acquirers are basically seeing their revenues increase but their margins are decreasing. There is a lot of processing horsepower, so there is more supply of processing than demand."