He said the organisation did not believe attendance at the world games was a right for the country's best combinations in each discipline. Each had to prove themselves on the world stage to earn selection.
Ellis was commenting following an editorial published in Horse & Pony magazine, in which editor Rowan Dixon questioned the ESNZ selection policy which is almost certain to result in limited Kiwi representation of the World Equestrian Games in Kentucky later this year.
"Minnows in a global sport CAN learn and develop by 'merely' participating at a world championship," Dixon wrote.
"We are certainly not going to get any better by sitting at home and watching," she said.
Dixon said she strongly disagreed with the ESNZ selection policy which seems certain to see New Zealand take a tiny team to the world games.
Dixon noted the issues around high performance funding through SPARC (Sport & Recreation New Zealand), but says the issue is not purely financial.
"I happen to know at least one rider, who has met the FEI's qualifying standards, has offered to fundraise for a WEG campaign, but cannot get selected due to the current policy which requires riders to be capable of a finishing in the top third of the field, more or less."
Ellis, responding to Dixon's policy criticism, said ESNZ lost its high performance funding from SPARC for showjumping as a result of performances in Hong Kong during the 2008 Olympics, leaving only eventing as recipients of government high-performance funding.
After its own of review following the Olympics, Paralympic and World Endurance Championships, ESNZ re-launched its high performance programme with a stronger focus on medal-winning at pinnacle events, which include the World Equestrian Games.
"A basic tenet of the new high-performance programme is the ability of individual rider/horse combinations to produce credible performances at pinnacle events."
A credible performance was one that reflected positively on the standard of the discipline within New Zealand.
"Clearly this is subjective, but ESNZ has defined its view of 'credible' in the selection criteria for each discipline."
He said rider and horse combinations needed to prove their relative standard in a global context rather than just within New Zealand.
"The FEI sets 'minimum eligibility standards' (MES) for WEG, often known as certificates of capability. These are not qualifying standards in the way that they are often portrayed. MES are used to ensure all combinations have achieved a minimum standard to ensure safety and competence at WEG," Ellis said.
"Most major equestrian nations use these MES as a 'necessary but not sufficient' part of their selection criteria.
"It is ESNZ's view that the achievement of FEI MES is not sufficient to prove the potential for credible international results at WEG.
"As an example, in para-dressage, four New Zealand riders have achieved their MES. However, at this stage none of these four are listed in the 2010 high-performance squad, meaning that, if final selection were to occur today, ESNZ would not select any para-dressage riders to WEG."
Ellis said selectors in each discipline had set standards above MES levels to ensure that selected combinations had the capability to achieve ESNZ's targets for that discipline.
In eventing, ESNZ requires that individual combinations have the proven ability to finish in the top 16 of the individual competition.
"In doing so, combinations will contribute towards a team target set by SPARC as the basis of their funding," he said.
"In showjumping, eventing and para-dressage, New Zealand riders are currently competing - or planning to compete - across the world to advance their own selection chances according to specific selection criteria.
"For example, Katie McVean and Dunstan Delphi enjoyed a special showjumping season winning all major domestic honours. At season end, their performances within New Zealand were not deemed to have fully proven that the combination could meet ESNZ targets for WEG and the combination was placed in the 2010 'B' squad, meaning further performance is required.
"Katie and Delphi have enjoyed an excellent start to their North American campaign to prove that performance level."
Ellis said high performance investment received from SPARC is targeted to eventing, which meant ESNZ did not fund any other discipline's combinations should they be selected as part of the Kiwi team for WEG.
"The ability to self-fund a trip to WEG is not a part of the selection criteria."
He continued: "ESNZ does not believe that attendance at WEG is a right for the best New Zealand rider/horse combination in each discipline; selection needs to be by proven performance against international standards.
He said ESNZ did not believe any pinnacle event - WEG or Olympics - should be treated as a developmental experience, given the large number of other international opportunities that exist in the sport.
"ESNZ has not made any final decisions with regard to the attendance of any New Zealand dressage combination for WEG; selection will be finalised on September 1, 2010.
"At this stage, dressage has only one combination, Jody Hartstone and Whisper, in the ESNZ dressage high performance squads.
"Noting the combination's special circumstances - the horse being brought to NZ late in the season - Dressage selectors have already offered significant flexibility to the previously published selection criteria and are currently clarifying specific CDI shows overseas at which the combination will be able to prove their capability of achieving a credible performance at WEG."