Several days later, Ms Peet's family contacted the friend to say they had lost contact, with her mother then reporting the journalist missing.
A Foreign Office spokesperson said: "We are supporting the family of a British woman who has been reported as missing in Brazil and are in contact with the local authorities.
Ms Peet's father told Sky News she was traced to Gatwick Airport and was found to have boarded a plane to Sao Paulo before the trail went cold.
Ms Peet had worked as a freelance foreign correspondent in Brazil for almost two years and returned to the country in November.
Brazilian authorities have said they are "visiting locations to find and clarify what happened" to missing British journalist Charlotte Peet.
