However, the testimonial organising committee, after discussions with the police, have decided Smith will not take part with Radebe being informed of the news yesterday.
David Share, the chairman of Radebe's testimonial committee, said: "If we want to put the game on we have to do it with the co-operation of the police and we have been in discussions with regards match-day security. Alan Smith would love to play, but it would not be prudent so soon after him moving from Leeds to Manchester United to have him involved.
"He is very disappointed, Lucas is very disappointed and I would imagine the vast majority of Leeds supporters are disappointed too. We are only dealing with a small minority, but it is the decision that has been taken. We are not able to invite certain players back – it is a fact of life."
The chairman of Leeds United supporters club, Ray Fell, said: "I regret that decisions like this have to be taken, but I can understand why it has been done. It is sad that there would perhaps have been a minority who would have given Alan Smith a hostile reception.
"I am pretty sure that the majority of our fans understand that Alan gave everything for Leeds United and then picked the club that was the best for his career."
Radebe's testimonial will still attract a host of star names with FIFA set to give their backing.