Amundsen received a telegram from the Norwegian Foreign Ministry: "The Norwegian Minister in Buenos Aires Christophersen writes: Herr landowner Peter Christophersen of this place has expressed to me his willingness to provide the Expedition both with Coal and the necessary supplies at his expense on condition that 'Fram' on her forthcoming voyage touches Montevideo to take on coal. On behalf of the expedition I have accepted Herr Christophersen's kind and altruistic offer of which the Foreign Ministry is asked to apprize Herr Roald Amundsen". 
Peter Christophersen, known as "Don Pedro", had emigrated from Norway to Argentina in 1871 and become a wealthy landowner.
"I have received your magnificent no less than kind offer," Amundsen replied, "to supply my Expedition both with [fuel] and provisions when Fram touches Montevideo, and I hereby permit myself to convey my recognition and warmest thanks for the generous manner in which it is your intention to support my enterprise." 
Without giving away his true plans, Amundsen explained that he needed oil, not coal, and that the Fram was bound for Buenos Aires. Generously, Don Pedro offered "petroleum and provisions in Montevideo or Buenos Aires." 
Under pledge of secrecy, Amundsen told Prestrud and Gjertsen that they were going south.
 Norwegian Foreign Ministry, draft of telegram, 30 July 1910, quoted by Roland Huntford in Scott and Amundsen (New York : Putnam, 1980, c1979), p.289-290.
 Roald Amundsen, letter to Don Pedro Christophersen, 30 July 1910, quoted by Roland Huntford in Scott and Amundsen (New York : Putnam, 1980, c1979), p.290.
 Norwegian Foreign Ministry, telegram to Roald Amundsen, 2 August 1910, quoted by Roland Huntford in Scott and Amundsen (New York : Putnam, 1980, c1979), p.290.