Adkins was named Reading manager yesterday.
"I spoke to Nigel a few weeks ago and told him what a great club Leeds are - what a great opportunity it would be for him here," Warnock told the Yorkshire Evening Post.
"The club need an outstanding candidate and I think you'd put him in that category. But he's obviously weighed everything up and decided that Reading's the best move for him.
"To be fair to Reading, they're a well-run and established club and he'll be safe even if they come down. Then he'll have money, a good squad and every chance of getting them back up. I can see the appeal but I think he'd have been great for Leeds too.
"He was definitely interested. But then you don't really need to sell Leeds United to anyone. The club sells itself."