Ashley refuses to dip into his personal wealth, saying will not take on “the equivalent of countries” in the transfer market.
But he repeated that every penny Benitez generates is his to do what he wants with.
He said: “Every penny the club generates, he can have, but it won’t generate enough. It’s Newcastle United.
“It doesn’t have a £40m a year stadium naming rights deal. So I don’t want the fans to think ‘that’s great, Rafa’s getting £150m in the morning’. He’s not.
“With Lee Charnley’s help – and Lee Charnley answers to Rafa not the other way around, so we’re crystal clear – Rafa makes all the final decisions on the players out and the players in, but he has to do it with the money the club has.
“If you say to me ‘I’m wealthy’ well, okay. In theory I’m a whatever, a billionaire, maybe even a multi-billionaire, but in reality my wealth is in Sports Direct shares which, as I said the other week, are like wallpaper.
“I don’t have that cash in the bank, so I don’t have that ability to write a cheque for £200m. I don’t have it. It’s very simple, it’s not there.
“I’d have to sell Sports Direct shares to fund that. So people outside of football looking in and the way sometimes it’s portrayed, is that those sort of wealth terms are in the bank – they’re not.
“I’ve got to make it crystal clear that I am nowhere near wealthy enough in football now to compete with the likes of Manchester City – and not just Man City. Basically, it’s a wealthy individual taking on what is the equivalent of countries. I cannot and I will not.”
Ashley has been made aware of Benitez’s intense frustration over the club’s lack of financial muscle following promotion.
Benitez said:“The momentum was there, everybody was so excited. That was an important period for us, but we couldn’t do what we wanted to do for different reasons and the reality is, we are where we are.”
But Spaniard insisted again that he is committed to United, but warned fans ahead of tomorrow’s home game against Tottenham that he won’t be able to work miracles.
“I am not saying I am really pleased with everything because it’s not true, but I am not saying that I will not do my best to be as high as possible in the table,” he said.