National Security Agency buys web browsing data without warrant, letter shows

An illustration picture shows the logo of the U.S. National Security Agency on the display of an iPhone in Berlin, June 7, 2013. REUTERS/Pawel Kopczynski/FILE PHOTO

SAN FRANCISCO (Reuters) - The U.S. National Security Agency buys Americans' internet browsing information from commercial brokers without a warrant, the agency's director told Democratic Senator Ron Wyden in a letter made public on Thursday.

Wyden, who released the Dec. 11 letter, called upon U.S. intelligence officials to stop using Americans' personal data without their express knowledge and consent, saying it was unlawful.