Channel TN said it got the documents from a team of reporters in Brazil who have been working with Mr. Snowden. One of the documents, labeled “top secret” and dated 2010, described “efforts to collect high-priority military and leadership communications,” the channel said. Tensions over the Falklands still simmer more than 30 years after the two countries fought a brief war, won by Britain, for control of the South Atlantic archipelago. Oil has been discovered in the area, raising the stakes in the dispute over control of the islands. A spokesman for Britain’s Foreign Office said the government would neither confirm nor deny the reports. No one from the Argentine government was available to comment.