Ngugi, who has been out of action for 27 months because of a ban imposed for refusing to take a random drug test, said he would not run in a 10- kilometre event around the Scottish capital on Sunday.
Ngugi said that December would be the time of his comeback, when he hoped to make Kenya's team for the World Cross-Country Championships where he would be seeking a record sixth title.
"I am not ready now, I have already explained this," Ngugi said. "The aim is December, then the World Cross-Country championships, then prospects for an Atlanta gold."
He said he was troubled by a knee injury and understood he would be travelling to Edinburgh only to sign autographs. "I am not even sure that I will go yet," he said. Meanwhile, in London, his agent, John Bicourt, was still insisting that the Kenyan would compete.Reuse content