The NZ Transport Agency is tight lipped at the extent of driver licensing fraud currently under investigation by police and IT forensic experts.

Police are investigating driver licensing fraud at the NZ Transport Agency which recently sacked a contractor after concerns were raised.

The agency confirmed it was a suspected case of internal fraud relating to a "limited" number of driver licences and vehicle records.

"In late November our internal processes identified serious concerns about the behaviour and actions of a contractor, whose employment was terminated within 24 hours of these concerns being raised," the agency said in a written statement.

NZTA has engaged external assistance for a forensic investigation to help determine the extent of the suspected fraud, but declined to comment further while it worked with police to establish all of the facts.

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SUPPLIED Previous cases of driver licence fraud led to hundreds of motorists having to resit licences but NZTA has indicated the current fraud investigation involves a limited number of licences.

However, Stuff understands the investigation centres on unauthorised access to the driver licence register which approves licences for issuing to applicants.

In February, NZTA announced a raft of changes it had implemented in the wake of reports that driving licences were being obtained by bribes or corruption.

The changes included closer monitoring of all driver licensing transactions at a national level to identify trends and potential anomalies.

Hundreds of drivers had licences cancelled or were required to re-sit tests and a trial of two men accused of taking bribes in exchange for driver's licences is underway in the Manukau District Court.

The latest fraud revelations come at a bad time for the agency which is already the subject of two reviews relating to its failure to enforce transport safety regulations.

Law firm Meredith Connell has stepped in to oversee NZTA's compliance work, leading to growing suspensions of warrant of fitness certifiers and threats to shut down 20 trucking companies.

Transport Minister Phil Twyford has expressed concern at longstanding systemic problems at the agency and has also appointed the MOT to undertake a review of its work.