The Nelson Mandela Foundation paid tribute on Wednesday to poet and author Maya Angelou.
"On behalf of our board of trustees and staff, the Nelson Mandela Foundation mourns the passing of Maya Angelou," spokeswoman Danielle Melville said in a statement.
Angelou, who rose from poverty, segregation and violence to become a force on stage, screen and the printed page, died at the age of 86.
Wake Forest University, where Angelou worked as a professor of American Studies since 1982, announced her death in a news release on Wednesday.
Melville said Mandela met Angelou in Cairo, Egypt in 1962, while he was garnering support for the armed struggle and undergoing military training.
Angelou was married to Pan Africanist Congress activist, Vusumzi Make, at the time.
"Our archives reveal that today in 1986 Mr Mandela watched in prison, the film version of her work 'I Know Why the Caged Bird Sings'," she said.
"I Know Why the Caged Bird Sings" became standard (and occasionally censored) reading, and was the first of a multipart autobiography that continued through the decades.
Mandela met the poet again in Washington in 1993, when he was released from prison and attended the inauguration of former United States President Bill Clinton.
"He told Richard Stengel, his collaborator on his autobiography 'Long Walk to Freedom', that he telephoned her in her hotel after she had 'delivered a very powerful poem'," said Melville.
Angelou also wrote and dedicated a poem to Mandela, titled "His Day is Done", when he died in December last year.
"Nelson Mandela's day is done. The news, expected and still unwelcome, reached us in the United States, and suddenly our world became somber.
Our skies were leadened," read some of the lines of the poem.
Mandela died on December 5 in his Houghton home in Johannesburg and was buried in Qunu in the Eastern Cape.