 Rio Tinto PLC LSE:RIO said it agreed to provide up to US400mln in interim debt funding to Turquoise Hill Resources Ltd TSX:TRQ, the developer of the Oyu Tolgoi copper-gold mine in Mongolia. In March, Rio Tinto announced a US2.7bn offer to buy the 49 interest it does not already hold in Canadas Turquoise Hill Resources with the aim of moving the Oyu Tolgoi copper project forward. 