He has been suspended from the team pending analysis of his backup B sample.
The news follows the high-profile case of star Astana rider Alexandre Vinokurov, who was thrown out of the Tour de France after testing positive for a blood transfusion. The entire Astana team was withdrawn from the race, and Vinokourov was fired by the team after his B sample confirmed the initial positive finding.
Both Vinokourov and Kashechkin failed a test for homologous blood doping, meaning they both used the blood from another person.
Kashechkin finished third overall in this year's Dauphine Libere race. He finished fourth in the 13th stage of the Tour de France.
"Whereas the Astana Cycling Team makes great efforts to be rebuilt on new bases, the positive control of Kashechkin once more damages the credibility of the team," the team said in a statement. "This new hard blow does nothing but reinforce the will of the Astana Cycling Team's management to set up drastic measures for a clean cycling."
Kashechkin faces a two-year ban and could lose a year's salary under the anti-doping charter of the International Cycling Union.
UCI president Pat McQuaid was not immediately available for comment.
Astana suspended its activities for a month following the Vinokourov scandal, meaning none of its riders will compete in any ProTour events in August.
Astana said it would announce new team regulations and ethics rules at a later date. The first race after the team's self-imposed suspension is the Spanish Vuelta, scheduled to start on Sept. 1.
Blood transfusions work by increasing an athlete's red blood cells, which carry oxygen to the muscles.