* GDF raises Jirau dam stake to 60 pct from 50.1 pct * Main builder Camargo Correa sells stake as planned * Dam expected to start operations in Jan. 2013 SAO PAULO, Oct 1 (Reuters) - French energy company GDF Suez Group is raising its stake in Brazil's Jirau hydroelectric dam to 60 percent from 50.1 percent, as the project's main builder Camargo Correa sells its ownership stake. The consolidation of ownership, combined with a 2.3 billion real ($1.13 billion) loan announced by state development bank BNDES on Friday, suggests the dam on the Madeira River, one of the Amazon's main tributaries, is nearing the start of operations. "From the beginning of the project, shareholders agreed that Camargo Correa would leave the Jirau project in the final stages of construction, once the principal construction risks were reduced," said GDF affiliate Tractebel Energia in a market filing announcing the transaction on Monday. The dam is being built to provide generation capacity of 3,750 megawatts. That's enough to supply the electricity needs of a city of more than 5 million people, according to electricity-use rates used by the Brazilian government. Work at Jirau has been delayed by labor protests and environmental objections, like many major hydro dams in Brazil, which has pushed back completion and reduced the return on investment. The filing did not disclose a price at which GDF bought the stake from Camargo Correa, which remains the leading construction company on the project. The transaction remains subject to regulatory approval, which is expected by year-end. GDF's remaining partners in the Jirau dam are two affiliates of Eletrobras, Brazil's state-led electric utility holding company, both of which hold 20 percent. GDF is expected to eventually transfer its stake to Tractebel. The Jirau dam is the second-largest electric generation project under way in Brazil. The power plant's first unit is expected to start functioning in January 2013 and full operation is expected in March 2015. Shares of GDF Suez rose 1.2 percent in Monday trading, while Tractebel shares were little changed after the announcement.