BHA chair Annamarie Phelps has hit back at critics of the controversial changes to apprentice pay and said "a significant number" of trainers were not paying their expenses.
Trainers are angry the current system, under which Flat handlers retain up to 50 per cent of an apprentice's riding fee and prize-money yield in return for paying towards their expenses, is to end next March.
Andrew Balding is among those to have criticised the authority, telling four aspiring jockeys he can no longer offer them employment due to the new rules on claimers' pay.
In a letter to chief executive Nick Rust, which he shared with the Racing Post, he accused the BHA of taking trainers for "fools".
Richard Hannon and Richard Fahey have also voiced dissatisfaction at the new rules, believing they underestimate the role trainers play in advancing the career of apprentices and the cost to them financially, but Phelps, speaking on Racing TV's Luck on Sunday, said: "I think it's really disappointing from the BHA perspective that they feel the way they do.
"The media have focused a lot on the people that have a problem with it and less so on the number of trainers who have actually been supportive of this move.
"We have to look not necessarily at this reaction but go back to why we wanted to make this change – the PJA came to us, explaining they had an awful lot of people raising this issue. The agreement wasn't being followed.
"There were a significant number of trainers who were not paying their apprentice jockeys expenses. I know people have said they're not vulnerable but actually they are. There is very much a power relationship between their trainer and these young people coming into the sport at that age."
The dispute comes at the end of a year when there has been tension between trainers and the BHA over issues such as flu and equine welfare.
Phelps made a vigorous defence of the BHA's role as an honest broker in a dispute between the jockeys' and trainers' organisations.
She said: "The negotiations between the NTF and the PJA went on for a very long time, neither of them could come to a compromise or an agreement, so finally what was the nearest to the compromise was sent to the board of the BHA to arbitrate on because no decision could be made.
"We made the best decision. We discussed it for a long time, we pushed back very much on both sides of the argument and decided to approve this.
"I can see there are some people who have built their business models on this and they do give an awful lot to the apprentice jockeys they've got, but likewise there are a significant number who are not looking after them in the same way and it's always a shame when that happens.
"Those are the people we should be focusing on, not on the BHA trying to make sure we are looking after our young people coming in to the sport."
Phelps also stressed the forward-looking nature of the change, which brings the rules for apprentices closer to those that apply for conditional jockeys over jumps.
"We have to move towards 21st century employment practices," she said. "We can't live always in the past.
"There is a power imbalance always between young people coming in and powerful trainers. The fact very few people have come forward openly to say 'my trainer isn't giving me this money', they are going through the PJA, they don't feel able to fight it through the trainers.
"We need to make it a bit more simple and make the agreement more transparent."