Narrabri mine expansion would make it dirtiest thermal coalmine in Australia, environmentalists say

The proposed underground expansion of the Narrabri coalmine would extend its life by 13 years and could release high levels of methane. Photograph: Rob Griffith/AP

A $400m mine expansion earmarked for approval by the New South Wales government would become the dirtiest thermal coal project in Australia, a public hearing has heard.

Whitehaven Coal’s Narrabri underground expansion was incompatible with the state government’s 2030 climate targets and should be rejected, environment group Lock the Gate told the NSW Independent Planning Commission (IPC) on Monday.