The State Department on Tuesday defended its decision to participate in the Riyadh International Book Fair last month, an event that many are criticizing because of the many anti-Semitic books that were sold there, including Adolf Hitler's autobiography "Mein Kampf."

This week, a human rights group criticized U.S. participation in that fair, which also sold books such as "The Protocols of the Elders of Zion, News and Freemasonry."

In a briefing with reporters, State spokesman Mark Toner said the U.S. condemns anti-Semitism "in all its forms," stressed that the U.S. government was only a participant in the fair, and said officials were not aware that those books would be sold.

"We were just a participant, we weren't aware that these books were going to be featured in this book fair, so we're not a partner, we're not a funder, we're not a sponsor, we're just simply a participant," Toner said.

Toner said he wasn't sure if the U.S. government lodged a formal complaint with Riyadh.

"My understanding is that we were not aware that these books were going to be featured at the fair, and I can also check on whether we raised this directly, our concerns with the Saudi government," he said.

When asked whether the U.S. would participate in the fair again, Toner indicated that the U.S. could decide to pull out next year, although that would be up to the next administration.

"I think we would weigh this very heavily, considering this incident," he said.

Still, Toner stressed the importance of the fair to the U.S., which brings books about democracy and children's books each year. He did note that the U.S. pays a fee for space at the fair to sell those books.

"We wouldn't do it if it wasn't a productive engagement with Saudi society," he said. "Representatives of the U.S. embassy in Riyahd have participated in the international Riyahd book fair for multiple years, as part of an effort to essentially distribute books to Saudi citizens, that include books about democracy, tolerance, diversity, human rights, etc."