CuChullaine O'Reilly, founder of the Long Riders' Guild, has attacked the race, voicing fears for the wellbeing and safety of the horses and riders.
O'Reilly has raised concerns around the experience of some riders, the ability of the small local horses to carry larger-framed foreigners between race stations, and the dangerous and difficult nature of the terrain.
However, The Adventurists, the firm organising the event, says veterinarian support will be in place for the relay race and riders will carry tracking devices for their safety.
Discussion forums and bloggers have weighed into the debate over the race, which will involve up to 800 horses, with some questioning whether the event is in the best interests of the Mongol herdsmen who eke out a living in the remote terrain.
On its website, The Adventurists played up the danger and adventure in the race, which will involved 25 riders racing native horses for 40km legs between horse stations manned by local herdsman.
"Having thundered out over the start line," the Adventurists website exhorted, "a crotch-pounding 1000km will stand between you and glorious victory.
"You will have to navigate your way from one station to the next single-handedly; there's no marked course and there will be huge stretches with no paths or tracks at all.
"In fact even when there are tracks there is little chance they will be going in the right direction. You will be facing the wilderness, alone ...
"Bleeding kidneys, broken limbs, open sores, sun stroke, moon stroke and a list of dangers longer than your arm stand between the you and victory."
Its more recent material reflects a more measured explanation of the logistics, including addressing issues of water supply, equine welfare and ensuring support for contestants is not far away during the race. The route, it transpires, will have a "definite structure".
Each rider will carry a satellite tracking device with an emergency help button should they need to summon a support vehicle.
An Adventurists spokesperson said: "Our websites may be written in a humourous tone but we do take what we do incredibly seriously, particularly when it comes to animal welfare for the Mongol Derby.
"We think that perhaps this tone is sometimes misunderstood. It's also important to point out that horse welfare has been at the very top of the agenda."
However, O'Reilly's criticism is no less trenchant, even given the greater detail now available around the running of the race.
"What needs to be fully understood," says O'Reilly, "is that we are not discussing common tourists.
"Traditional travellers go to a country in order to interact with the people, sample the food and experience the culture. This is an experience that is customarily a slow learning process. That is not what [company founder Tom] Morgan and his race contestants are doing.
"They will use every possible means to rush through Mongolia, highlight any danger ... make themselves look like heroes at the expense of the land, its people and its horses."
O'Reilly says no amount of window-dressing by The Adventurists can disguise the fact that the race is "an act of equestrian colonialism".
He continued: "In a scene reminiscent of buying Manhattan from the Indians for $26 in beads ... naïve Mongolians are being enticed into selling their sacred equestrian heritage for pennies."
The Adventurists counter that all vets, herders, horse breeders and trainers involved in the Mongol Derby are being "well paid" for their involvement.
O'Reilly, who has labelled the event an ill-advised equestrian misadventure, said long riders with Mongolian experience were asked by the guild to study the proposed event.
"Their decision was unanimous," O'Reilly wrote in a widely published article.
"To consider putting foreigners with limited equestrian experience into an endurance race of this distance is asking one to deny the basic fact involved in this situation - namely that a race across this terrain, on those kind of horses, over that distance, would have taxed the original messengers of Genghis Khan, none of whom actually rode a thousand miles on one journey."
Debate has also raged over the role of a non-governmental organisation called VET Net, which has spent 17 years overseeing the training of Mongolian veterinarians in modern veterinary medicine.
Earlier material put out by The Adventurists said the company was working with VET Net over the care of horses involved in the race.
However, O'Reilly subsequently interviewd veterinarian Thomas Juergens, an adviser to VET Net who has worked the last 10 summers in Mongolia upskilling local veterinarians.
Dr Juergens said he understood VET Net was contacted in either January or February of 2009 by The Adventurists. "It is my understanding that they wanted us to supply all the veterinarians and oversee the medical needs throughout the entire race.
"But it is also my understanding that VET Net is not involved with providing veterinary care to the horses in this race."
Dr Juergens voiced his concerns over the welfare of horses in such a race and said the event "shows no respect for the nation's equestrian traditions, either".
"Because the contestants don't own the horses, they'll think they can ride them hard, then just walk away. What I see ... is disrespect for the horses and Mongolian traditions."
Dr Juergens also ventured the view: "Just because the remote Mongolian veterinarians have studied modern veterinary medicine for six weeks with VET Net doesn't mean they are qualified to act as attending veterinarians for the critical health needs of the horses competing in this race."
However, The Adventurists countered by saying they had contacted VET Net in November 2008 "to seek advice on veterinary care for the 600-plus horses being ridden in the Mongol Derby".
"The Adventurists would like to make clear that the two parties have been in regular contact since November 2008, by email, telephone and in person. VET Net have consulted The Adventurists on the veterinary situation in Mongolia, on the availability of good quality medicines and on how best to provide veterinary care for the Mongol Derby horses.
"VET Net also provided The Adventurists with the names and contact details of all their trained soum (village) vets along the Mongol Derby course. According to an email from a representative of Vet Net to The Adventurists: 'The soum veterinarians are well qualified veterinarians. They are private practising veterinarians who have benefited from the world-class drugs and equipment that we have been able to import and supply for them after they have received training in their use'.
"This network of VET Net-trained vets will be providing vet care for the Mongol Derby horses over the 1000 kilometre Mongol Derby. They will be checking the horses during their pre-race training, immediately before they start, and after they have completed."