It took an average of 634 days for a coronial inquiry to be completed in the year to 30 June 2018.

This information was provided by Justice Minister Andrew Little in response to a parliamentary written question from National MP Mark Mitchell.

Mr Little says some deaths referred to the coroner are found to be the result of natural causes and these are closed more quickly than non-natural deaths where an inquiry is opened.

"In the 2017/2018 financial year, the average time to complete an investigation where no inquiry was necessary was 193 days," he says.

Another question from Mr Mitchell asked what the average number of currenly outstanding files was for each coroner in New Zealand.

Mr Little says there are no statutory timeframes for when coronial files must be completed. Taking the question to mean how many active cases coroners have on hand, at 30 April 2019 there were 4693 active coronial cases on hand. This equates to an average of 260 cases per coroner.