The NSW Audit Office has issued a scathing assessment of the Berejiklian government's reform of the native vegetation laws, finding land-clearing was "not effectively regulated" with "few tangible outcomes" for breaches.

In a report released on Thursday, the agency also found almost two years after the laws came into effect, there is no timetable for the release of native vegetation regulatory maps for the two largest categories making it difficult for landholders "to determine if their plans for clearing are lawful".

A drone's view of land-clearing on a property near the Newell Highway in northern NSW in 2017. Credit:Nick Moir

It noted that over 200,000 hectares - or about 700 times the size of Sydney's CBD - had been approved for thinning or clearing of native vegetation in the first 18 months of the codes being introduced in August 2017.

However, the auditors found "there is no evidence-based assurance that clearing of native vegetation is being carried out in accordance with approvals".