The Sunday Times is alleged to have targeted the personal information of the former Prime Minister Gordon Brown at the time he was chancellor, a BBC investigation has found.
Documents and a phone recording suggest “blagging” was used to obtain private financial and property details.
The Browns also fear medical records relating to their son Fraser, whom the Sun revealed in 2006 had cystic fibrosis, may have been obtained.
News International is yet to respond.
The company, a subsidiary of News Corporation, owns the Sun and the Sunday Times, and also owned the News of the World which was shut last week amid allegations of phone-hacking and illegal payments to police officers.