WELLINGTON, Sept 14 - Party leader James Shaw says despite huge progress over recent decades the survival of the language is still not assured.

"We have a responsibility to ensure that our indigenous language not just survives but thrives," he said on Wednesday.

"The Green Party put universal Te Reo Maori in all schools on the political agenda in February, and now is releasing a plan that shows how we will achieve that."

Shaw will release the plan on the steps of parliament on Thursday.