ABC News' Paula Faris and Doug Vollmayer report:

Superstar Mariah Carey is being called out by the Human Rights Foundation for her recent concert in Angola for its president, whom the organization calls "one of Africa's chief human rights violators and most corrupt tyrants."

Carey performed a two-hour concert at an event for the Angolan Red Cross this past Sunday and President José Eduardo dos Santos.

Dos Santos, who has been president since 1979, has ordered the deaths of many politicians, journalists and activists who have protested his rule, according to the Human Rights Foundation.

Carey was pictured smiling at the event with the president and his family, reportedly saying, "I am happy to be here in this room, and I am honored to share this show with the president of Angola."

Carey has not responded to ABC News' request for comment.

The gala was sponsored by the mobile phone company Unitel, which is owned by dos Santos' daughter, according to the Human Rights Foundation.

"Mariah Carey can't seem to get enough dictator cash, reportedly more than $1 million this time," Human Rights Foundation president Thor Halvorssen said in a news release Thursday, referring to Carey's performance for Libyan dictator Moammar Gadhafi five years ago.

The "All I Want for Christmas" singer later apologized for the Gadhafi performance, saying, "I feel horrible and embarrassed to have participated in this mess."

Other musicians, including 50 Cent, Usher and Beyonce have also accepted lucrative gigs performing for members of the Gadhafi family. They later donated the money.

Jennifer Lopez landed herself in hot water this past July when she sang for the president of Turkmenistan, a country Human Rights Watch calls one of the world's most repressed. She later apologized.