By Marietta Cauchi and Carol Dean Of DOW JONES NEWSWIRES LONDON (Dow Jones)--Royal Bank of Scotland Group PLC (RBS) has asked the two remaining bidders for its Global Merchant Services payments-processing unit to disclose proposals by July 19, ahead of a formal final deadline at the end of the month, people familiar with the situation said Friday. It is an informal deadline to enable RBS to check that both bids conform with its requirements and doesn't affect the final deadline, which will then lead to exclusivity, the people said. There are two buyout groups in the final stages of the auction, which initially attracted scores of private equity firms and trade buyers. TPG is working on a joint bid with Clayton, Dubilier & Rice, and Advent International and Bain Capital are bidding together on a deal. The unit is valued at up to GBP2.5 billion. The deal will be complex because it involves the carving out of assets as well as arrangements for the post-completion business, which will likely involve an ongoing relationship with RBS. Bidders will also be having do deal with the technology involved in running the business on a different platform. Global Merchant Services' biggest asset is RBS Worldpay, which processes credit-card payments in 40 different countries. The auction is being run by UBS AG (UBS) and is expected to complete with a deal closed in the third quarter. The RBS unit is being sold by the 83%-government owned bank as part of a disposal program forced on it after being bailed out by the state. -By Marietta Cauchi and Carol Dean, Dow Jones Newswires; +44 207 842 9241; [email protected] (Jessica Hodgson and Patricia Kowsmann contributed to this article.) (END) Dow Jones Newswires July 02, 2010 09:50 ET (13:50 GMT)