The state government has announced the end of the head of the NSW Police watchdog's tenure part-way through a strip-search inquiry, in what Labor and the Greens have described as a politically-motivated decision that could derail the high-profile probe.

Special Minister of State Don Harwin said Michael Adams, QC, would finish his three-year term as the inaugural chief commissioner of the Law Enforcement Conduct Commission on January 31, and would be immediately replaced by former NSW District Court chief judge Reginald Blanch, QC.

The tenure of LECC chief commissioner Michael Adams, QC, will end next month. Credit:Phil Carrick

In a statement on Monday announcing Mr Adams' departure, Mr Harwin said he was "grateful for the leadership Chief Commissioner Adams has shown during his tenure".

The announcement came almost two weeks after Mr Adams told a NSW parliamentary inquiry there was "significant corruption" within the ranks of NSW Police, saying "otherwise, for example, bikie gangs could not be the major manufacturers of methamphetamine in NSW".