Human rights activists have accused Mariah Carey of accepting a $1m (£600,000) fee to play a concert for Angola's "father-daughter kleptocracy". The Human Rights Foundation claims that, by performing at a recent benefit for the Angolan Red Cross, the singer was accepting "dictator cash".

On 16 December, Carey flew to Luanda, Angola's capital, for a headline appearance as part of the second annual Baile Vermelho. This gala "aims to raise funds and seek partnerships medium and long term that could serve the cause of the Angola Red Cross", according to the country's official press agency, and Carey's appearance apparently helped raise $65,000. She also played a stadium gig sponsored by the mobile phone provider Unitel. Platina Line, a local entertainment website, published numerous photos from the events, showing Carey singing in a bikini top and a Santa Claus dress, as well as posing with Isabel dos Santos, president of the Angola Red Cross, and Dos Santos's father, José Eduardo dos Santos.

But as the Human Rights Foundation has since pointed out, José Eduardo dos Santos is not just the parent of a minor African diplomat: he is Angola's president, an autocrat who has governed the country since 1979. Isabel dos Santos – nicknamed "the princess" – is Africa's richest woman and also a co-owner of Unitel. After studying in London, Isabel amassed a fortune of more than €1bn (£835,000) – in part, critics say, from the fruits of government corruption. Meanwhile, the majority of Angolans live on less than $2 a day.

"Mariah Carey can't seem to get enough dictator cash, reportedly more than $1m this time," Thor Halvorssen, president of the New York-based Human Rights Foundation, said in a statement. "It is the sad spectacle of an international artist purchased by a ruthless police state to entertain and whitewash the father-daughter kleptocracy that has amassed billions in ill-gotten wealth."

Carey's impolitic performance is particularly noteworthy due to her recent history: in 2011, she said she felt "horrible and embarrassed" for having played a $1m gig for the family of Libyan dictator Muammar Gaddafi. "I was naive and unaware of who I was booked to perform for," she said. "Going forward, this is a lesson for all artists to learn from. We need to be more aware and take more responsibility regardless of who books our shows. Ultimately, we as artists are to be held accountable."

"Just five years ago she performed for the family of [Gaddafi]," Halvorssen wrote. "Now, she goes from private performances to public displays of support and credibility for one of Africa's chief human rights violators and most corrupt tyrants."

Mariah Carey's representatives did not respond to requests for comment.