Bale will sit out of Wednesday's friendly because of a foot injury, and Tardelli, assistant to Giovanni Trapattoni, says the Tottenham star can be compared to the likes of Cristiano Ronaldo.
"He is a very good player," said the Italian. "At the moment he is up there with (Real forward) Cristiano Ronaldo and players of that calibre, and we saw this with what he did for Tottenham last season."
Of the reported world record £105m fee Real are ready to pay Spurs for Bale's services, Tardelli said: "Times change but maybe in my time Diego Maradona may have been worth that much.
"I don't know if Bale is worth that much but if someone pays it that is his value."