SYDNEY (AFP) - An Iranian asylum seeker detained in Papua New Guinea under Australian asylum laws has won Australia's most valuable literary prize for a book he reportedly wrote using the online messaging service WhatsApp.

Mr Behrouz Boochani, a Kurd who has been held on Papua New Guinea's Manus Island since 2013, was awarded the Victorian Prize for Literature on Thursday (Jan 31), said a statement on a government website for the Australian state of Victoria.

The journalist and filmmaker was awarded the A$100,000 (S$98,000) prize for his book No Friend But The Mountains: Writing From Manus Prison.

He will receive an additional A$25,000 after it also won the non-fiction category.

"(Boochani's) award was accepted by the book's translator Omid Tofighian, who worked with Boochani over five years to bring the stories to life," the state website said.

Media reports said Mr Boochani wrote the work on his phone and sent it to Mr Tofighian bit by bit in text messages.

This was because he felt unsafe in the guarded camp, which was shuttered last year after a local court ruling and the asylum seekers moved elsewhere on the island.

For years, Canberra has sent asylum seekers who try to enter the country by boat to Manus Island or Nauru in the Pacific for processing, with those found to be refugees barred from resettling in Australia.

The harsh policy is meant to deter people from embarking on treacherous sea journeys, but the United Nations and other rights groups have criticised the camps' conditions and long detention periods.

Mr Boochani's book beat 27 other shortlisted works published last year in Australia to win the overall prize.