A Sudanese refugee detainee has received a top human rights award for exposing what he has described as Australia's "inhumane" treatment of asylum seekers.

Abdul Aziz Muhamat, 26, was held at the Manus Island detention centre after fleeing violence in Darfur.

Over six years, he sent thousands of WhatsApp messages to a journalist who told his story in a podcast.

The Martin Ennals Award recognised his "extraordinary tenacity and courage".

Mr Muhamat described the camp's conditions, which have long been criticised by the United Nations.

Media playback is unsupported on your device

Media captionInside the Manus Island refugee camp

He said he was stripped of his name and referred to as a number- QNK002.

Prisoners were fed through a chain-link fence and treated worse than animals, he added.

Designed to deter refugees from reaching Australia by sea, Manus Island sits off Papua New Guinea.

Another island in the Pacific, Nauru, is also used as an offshore detention centre and the Australian prime minister has just announced he will reopen Christmas Island.

Dick Oosting, chair of the Martin Ennals Foundation, said that Mr Muhamat had "never stopped raising his voice for those who have been stripped of their most basic rights together with him".

Mr Muhamat has been permitted to leave the island since being granted a Swiss visa, but hopes to return to Manus to continue his advocacy work.

Jury member Phillip Lynch, head of the International Service for Human Rights (ISHR) organisation, said the decision to honour Mr Muhamat was "significant" and he hoped it would put pressure on Australia to halt the practice of offshore detention.

On Twitter, Mr Muhamat dedicated his award to the asylum seekers and refugees still on Manus.

Behrouz Boochani, an Iranian Kurd who was also held on Manus, was awarded the 2019 Victorian Prize for Literature for a book he wrote by WhatsApp from inside the detention centre.

The centre that both he and Mr Muhamat were held in closed in late 2017 but Mr Boochani remains on Manus Island in alternative accommodation.