WASHINGTON—Large-scale U.S. surveillance programs hinder the ability of journalists to communicate confidentially with sources and restrain lawyers from adequately representing clients, according to a report issued Monday by two advocacy groups.

As a result, journalists and lawyers face challenges—both to their ability to disseminate information and to hold the U.S. government accountable—said the report by Human Rights Watch and the American Civil Liberties Union. The groups said the government's "massively powerful surveillance...