The NSW Greens will step up the attack on coal, calling for exports to end in five years and existing mines to be phased out.

The coal election policy will be outlined on Sunday by Greens upper house MP Jeremy Buckingham, just days after Premier Mike Baird faced noisy protests opening the Whitehaven Coal mine at Maules Creek, which the government says will provide 400 jobs.

Greens MP Jeremy Buckingham says the Baird government is 'rabidly backing' coal mining in NSW. Credit:James Brickwood

Farmers have also been angered by last month's planning approval for Chinese coal miner Shenhua near the Liverpool Plains.

Mr Buckingham said the Greens were moving beyond the party's previous focus on "no new mines" to push for the complete phase out of coal, which would necessitate an economic plan for NSW coal producing regions to diversify into other, sustainable industries.