The NSW government is claiming waste recycling rates about twice real levels and is refusing to amend its published data despite being presented with more accurate industry-sourced information, green groups say.

In the latest State of the Environment report, the then Baird government boasted that 62.5 per cent of wasted was recycled in 2012-13. Commercial and industrial waste was "close to achieving" the 2014 recycling target of 63 per cent, it said.

Trash or treasure: some NSW landfills are being exhumed and the resulting material transported to Queensland. Credit:Graham Tidy

But the Boomerang Alliance of 47 groups across Australia challenged the report, presenting alternative data to the government and the NSW Environment Protection Authority's board last year.

The performance levels claimed by the government "were little more than a fiction", with the EPA in the "habit of using unverified and unsourced information to claim success in combating waste", the report provided to Fairfax Media said. A more realistic overall recycling rate was 36 per cent.