Up to 27 million people are living in slavery around the world, U.S. Secretary of State Hillary Clinton estimated as the U.S. unveiled its annual report into human trafficking, The Telegraph reports.

"The end of legal slavery in the United States and in other countries around the world has not, unfortunately, meant the end of slavery," Clinton said.

"Today it is estimated as many as 27 million people around the world are victims of modern slavery, what we sometimes call trafficking in persons," she said at the State Department. "Those victims of modern slavery are women and men, girls and boys, and their stories remind us of the kind of inhumane treatment we are capable of as human beings."

Out of the 185 countries included in the 2012 report, only 33 complied fully with laws in place to end human trafficking, putting them at the top of a four-tier ranking system.

Among the 16 other countries on the blacklist were Algeria, the Democratic Republic of the Congo, Libya, North Korea and Saudi Arabia.