New Zealand's justice minister resigned Monday after being charged over a car crash, in a fresh set-back for the government ahead of general elections in October.

Kiritapu 'Kiri' Allan said her position was now "untenable" and she had told Prime Minister Chris Hipkins she was resigning from her position "immediately".

Police also issued an infringement notice to Allan for returning an alcohol breath test that was over the limit, Hipkins said. The minister was briefly held in police custody after the crash.

Further details about the collision were not immediately available.

Allan is the fourth minister to leave cabinet in Hipkins' centre-left government since he replaced Jacinda Ardern as prime minister in January.

New Zealand goes to the polls on October 14.

Opinion polls this month put Hipkins' Labour government just behind the centre-right opposition National Party.