Nobel Prize for literature laureate Nadine Gordimer has died in her sleep. REUTERS/Radu Sigheti

Johannesburg - Nobel laureate and writer Nadine Gordimer was a progressive political thinker and outspoken on issues she felt strongly about, anti-apartheid activist Ahmed Kathrada said on Monday.

A friend of Gordimer's, Kathrada said in a statement by the Ahmed Kathrada Foundation that he was saddened by her passing.

“Nadine was a prolific writer,” said Kathrada.

“I met her before I went to prison, but it was after I was released that we came to know one another better, to the extent that I had the privilege of calling her my friend.

“She openly made known her beliefs regardless of who was going to disagree or be unhappy.”

Apart from being an admirer of the advent of democracy and the Constitution, Kathrada said “all her (Gordimer's) life, she defended freedom of speech.

“She was very much against arbitrary censorship. She was well-known for her anti-apartheid views; even during worst days of apartheid, she was quite outspoken.”

Earlier on Monday, law firm Edward Nathan Sonnenbergs said in a statement on behalf of the Gordimer family: “Her son Hugo and daughter Oriane and her caring helpers were with her... A private memorial service will be announced at a later date.”

Gordimer was 90 years old.