Ukrainian President Volodymyr Zelensky said Sunday he was "not ready" for talks with Russia unless its troops withdraw from his country, denying Western officials had suggested holding peace negotiations.

He was commenting on reports that US and European officials had spoken with his government about negotiations to end the war, and after a senior Ukrainian commander said the conflict was deadlocked.

"(The United States) know that I am not ready to speak with the terrorists because their word is nothing," Zelensky said in an interview with NBC's Meet the Press.

"For today, I don't have any relations with the Russians, and they know my position," he said, adding: "They have to go out from our territory, only after that, the world can switch on diplomacy."

He said the conflict had reached a "difficult situation", but again denied that it was deadlocked.

"On the frontline, it is not a secret, that we don't have air defense. That's why Russia controls the sky. If they control all the sky, until the moment when we get air defense, we can't move quickly forward," he said.

The sprawling frontline between the two warring sides has barely moved in almost a year, despite Ukraine launching a counteroffensive in June to claw back Russian-occupied territory.

Zelensky has regularly met Western leaders to try to secure more air defenses and stave off fatigue with the conflict, which has now lasted for more than 600 days.