Australia, New Zealand and Turkey have agreed that only 10,500 people chosen by a ballot can attend the Anzac Day centenary dawn service at Gallipoli.
The decision comes after complaints from tour companies that had taken bookings for the centenary dawn service in 2015, but could not guarantee their customers would be able to attend.
Veterans Affairs Minister Warren Snowdon says the three governments considered an independent report on the crowd capacity of the football field-sized commemorative site and agreed on the 10,500 limit.
"In addition to safety, the capacity also considers the geographic challenges of the site," he said in a statement.
"Surrounded by thick scrub, steep terrain, bounded by the Aegean Sea and protected by heritage and conservation measures ... the site cannot be expanded."
Turkey's embassy in Canberra said Australian individuals and groups could attend the site at any other time without limitations.
That appears to leave open the prospect for tour companies of organising their own commemorative events later in the day.
New Zealand Veterans Affairs Minister Michael Woodhouse said demand for places was expected to significantly exceed the site's safe capacity, which was why there would be a ballot for the 10,500 places.
Under the agreed plan, 8000 places will go to Australians, 2000 to New Zealanders and the remaining 500 for officials and VIPs.
Mr Snowdon said close to a million Australians could trace a direct family link to those who served on Gallipoli and many others were expected to want to attend the dawn service.
"A ballot is the fairest and most equitable method, ensuring a transparent and open process for allocating attendance places," he said.
Mr Snowdon said the ballot would probably be conducted early next year. All Australians can register and successful applicants will have plenty of time to make travel plans.
Opposition veterans affairs spokesman Michael Ronaldson called on the government to release the report it relied on, in reaching the 10,500 figure.
"All Australians, particularly those with pre-booked travel arrangements, deserve the opportunity to view the advice used by government and the assumptions made in arriving at this figure, including the extent of external consultation," he said in a statement.
Senator Ronaldson said there had been conflicting information about the capacity of the dawn service site.
He said a Department of Veterans Affairs 2005 Annual Report said more than 15,000 had attended a dawn service.