President Volodymyr Zelensky has acknowledged battlefield progress has been "slower than desired," weeks into Ukraine's military offensive to recapture areas occupied by Russia.

"Some people believe this is a Hollywood movie and expect results now. It's not," he told the BBC.

Zelenskyy said the military push was not going easily because 200,000 square km of Ukrainian territory had been mined by Russian forces. "Whatever some might want, including attempts to pressure us, with all due respect, we will advance on the battlefield the way we deem best," Zelenskyy added.

"No matter how far we advance in our counter-offensive, we will not agree to a frozen conflict because that is war, that is a prospectless development for Ukraine," he said.

Responding to a question about the possible use of nuclear weapons by Russia, Zelenskyy said that "Putin has been dangerous for us since 2014 when he occupied the first of our territories." "He will talk about the use of nuclear weapons, I don't think he is ready to do it because he is scared for his life, he loves it a lot. But there is no way I could say for sure, especially about a person with no ties to reality, who in the 21st Century, launched a full-scale war against their neighbor," Zelenskyy added.

He reinforced the need for Ukraine to be given security guarantees from Nato but said ultimately the goal was membership of the defensive alliance.

"[Jens] Stoltenberg knows my position," the Ukrainian leader said "We've told them numerous times: 'Don't knock the ground from under our feet.'"

The Ukrainian leader again made the case for Ukraine to receive US-made F-16s and said he believed fighter pilots could start training as soon as August, and that the first jets could arrive in six or seven months' time.

Zelenskyy said the quick recovery steps that need to be taken immediately include finding places for people to live, rebuilding the collapsed Kakhovka Dam and decentralizing the power grid.

"But on the larger scale we are speaking about the transformation of Ukraine," he explained.

Asked about Putin's words that Zelenskyy is a disgrace to the Jewish people, the president said: "It's like he doesn't fully understand his words. Apologies, but it's like he is the second king of antisemitism after Hitler. This is a president speaking. A civilised world cannot speak that way. But it was important for me to hear the reaction of the world and I am grateful for the support."