UPDATED 9.23am Twice as many New Zealand soldiers served at Gallipoli in World War One, than official archives suggest.

New research has this year revealed the numbers were nearer 16,000 than the 8,556 soldiers implied in the official war history of the campaign.

The study's been carried out by the Ministry for Culture and Heritage and the New Zealand Defence Force.

The original numbers were worked out using soldiers' service records.

However it has now been discovered that the theatre of war they served in, wasn't always recorded properly.

Researchers have matched the records with unit movements and official war diaries.

The major breakthrough came in January this year when NZDF Historian John Crawford discovered the notebooks of the Deputy Assistant Adjutant General (DAAG) of the Australian and New Zealand Division in Archives New Zealand.

“These meticulously kept records detail the movements of Australian and New Zealand Division soldiers on and off the Peninsula during June, July and August 1915 and meant we could calculate the total numbers with a much higher accuracy,” Mr Crawford said.

The senior advisor for heritage for the Defence Force, Matthew Buck, said it makes the battle more significant for New Zealanders, with so many more families and soldiers now known to have links to it.

"Gallipoli could hardly be more important as part of the New Zealand national story, so it has huge significance straight away just for that reason," he said.

"It begins to explain a bit more about the huge impact of that campaign, both at the time and still to the present day."

The research is believed to be the most comprehensive investigation ever undertaken into the total numbers of New Zealand soldiers who served at Gallipoli.