Complex sentence: Weiss was criticized in 2006 for his participation in the International Conference to Review the Global Vision of the Holocaust, widely considered to be an event promoting Holocaust denial internationally, although claimed to speak as "the voice of the people who died in the Holocaust".
Split into simpler sentences: Weiss was criticized in 2006 for his participation in the International Conference to Review the Global Vision of the Holocaust, widely considered to be an event promoting Holocaust denial internationally. However, Weiss claimed to speak as "the voice of the people who died in the Holocaust".