US rapper and songwriter Nicki Minaj ignored international critics Saturday and performed at a concert linked to the family of Angola's long-ruling President Jose Eduardo dos Santos.

The 33-year-old hip-hop star entertained several thousand people at a Christmas concert in the Angolan capital Luanda despite calls from rights groups to cancel the tour, which they saw as an endorsement of the authoritarian rule of dos Santos.

The concert was hosted by the Angola's largest mobile phone company, which is part owned by the dos Santos family.

Before going on stage, Minaj posted a photo of herself in a jumpsuit and draped in the black-and-red flag of Angola on photo-sharing service Instagram.

Concert organisers said they had sold 6,000 tickets for the concert, which was held in the 12,000-seat Coqueiros Stadium where she shared the stage with several local acts.

Minaj had come in for criticism for agreeing to perform, with Human Rights Foundation president Thor Halvorssen saying this week that she had "no good reason... to do business with the corrupt Angolan dictatorship and endorse the ruler's family company".

Jeffery Smith of the Robert F. Kennedy Human Rights centre also accused Minaj of "following in the footsteps of Mariah Carey, callously taking money from a dictator".

Fellow US singer Carey was criticised in 2013 for performing in front of dos Santos, who has governed the southern African nation for 36 years.

Smith said dos Santos had mounted a "sustained crackdown on basic human rights" arresting activists, opposition members, journalists, as well as musicians.

Minaj performed a day after a judge ordered the release of 15 Angolan activists, including prominent rapper Luaty Beirao, who were arrested six months ago during a book reading where one of the books on the agenda was about non-violent resistance to repressive regimes.

The group of youthful activists return to court next month for the conclusion of their trial on charges of "rebellion" and attempting to carry out a "coup".

Dos Santos, 73, has been accused of overseeing corruption, misrule and intimidation in a country that suffers endemic poverty despite being Africa's second-largest oil producer.

Angola marked 40 years of independence from Portugal last month, with dos Santos vowing to bring progress to the country, but critics accuse him of ruling through fear and repression.