Almost 90 per cent of the asylum seekers Australia has sent to Papua New Guinea are genuine refugees, new figures suggest.

Figures tendered to the PNG Supreme Court this week, and obtained by Fairfax, show that just 12.3 per cent of the detainees on Manus Island who have been processed were found not to have valid claims for protection.

This means that 87.7 per cent of people who have been assessed are refugees - an almost identical proportion to the number of boat arrivals to Australia who were later found to be genuine refugees. Figures from 2012-13 show 88 per cent of boat arrivals were found to be genuine refugees.

Despite this, many of the men on Manus Island have languished there for almost three years.