"I think that Ukraine's armed forces stand no chance here, as well as in other directions -- I have no doubt about that," Putin told an annual economic forum in Saint Petersburg.

AFP and representatives of other countries the Kremlin deems "unfriendly" were not accredited to cover the forum.

Putin claimed Ukraine's armed forces were suffering "heavy losses".

"In some places Ukrainian units are managing to reach the first line (of defence), in other places they are failing," he said.

"They are using the so-called strategic reserves," he added.

Putin said Ukrainian forces did not achieve their objectives in any section of the front, adding: "That's the important thing."