Manus Island detainees will receive $70 million in the settlement of a class action against the Australian government.

Lawyers for the detainees have reached a conditional settlement with the Australian government and the operators of the Manus Island Regional Processing Centre.

Slater and Gordon principal lawyer Andrew Baker said the case had been settled for $70 million plus costs.

The class action was seeking damages on behalf of 1905 group members who, legal firm Slater and Gordon says, cover the majority of people detained on Manus Island since 2012.

The detainees wanted compensation from the Australian government and the detention centre managers for alleged physical and psychological injuries they argue they suffered as a result of the conditions in which they were held.