The Mirror says Zhirkov's representatives claimed the FA Cup finalists have signed him in a secret deal for around £19million on a four-year contract.
Cska chief spokesman Sergei Aksyonov said: "We officially deny this story. Yury Zhirkov has not signed any deals with Chelsea.
"I have no further comment on this. We do not comment on wild rumours, we respond to facts. And there is nothing factual there."