Veronika Leila Szente Goldston, an advocacy director with HRW, told RFE/RL's Uzbek Service said that her group initially through the news that Karimov had been awarded UNESCO's Borobudur Gold Medal was "a bad joke."
She described the decision as "absolutely scandalous."
Matsuura awarded Karimov with the Borobudur medal during a visit to Tashkent on September 9.
Vladimir Sergeyev, a spokesman for UNESCO, told RFE/RL's Uzbek Service Matsuura wanted to thank Karimov for his contribution to the preservation of Uzbekistan's cultural heritage.
UNESCO's Borobudur medal was named after a Buddhist sanctuary in Indonesia that the organization helped restore in the 1970s and 1980s.