Russian President Vladimir Putin said on Tuesday that Ukraine was only likely to start peace talks when it ran out of resources and would use any potential cessation of hostilities to rearm again with Western help.

The war has sown devastation across swathes of eastern and southern Ukraine, killed or injured hundreds of thousands and triggered the biggest rupture in Russia's ties with the West since the 1962 Cuban Missile Crisis.

Putin, speaking at an economic forum in Russia's Pacific port city of Vladivostok, said Ukraine's counteroffensive against Russian forces had so far failed and that the Ukrainian army had sustained heavy losses.

"I have the impression that they want to bite off as much as they can and then, when their resources are close to zero, to achieve a cessation of hostilities and start negotiations in order to replenish their resources and restore combat capability," Putin said.

Putin said many potential mediators had asked him if Russia was ready to stop fighting, but he said that Russia could hardly stop fighting when it was facing a Ukrainian counteroffensive.

For there to be any chance of talks, said Putin, Ukraine would first have to cancel its self-imposed legal ban on peace talks and explain what it wanted.

"Then we shall see," Putin said.

Russia controls about 18% of Ukrainian territory, including Crimea which it annexed in 2014 and a swathe of eastern and southern Ukraine which it took control of in 2022.

For several months, Ukraine has been battling to try to regain some of that territory and has retaken some villages but not yet made significant territorial breakthroughs against heavily fortified Russian lines which are strewn with thousands of landmines.

Ukraine says it will not rest until every last Russian soldier is ejected from its land. The West says it wants to help Ukraine defeat Russia - an aim Kremlin officials say is an unrealistic pipedream.

Putin said that the West's decision to supply Ukraine with cluster bombs and depleted uranium munitions was a crime, but that while such supplies might prolong the war they would not change its ultimate outcome.

He also criticised the West's decision to supply Ukraine with F-16 jets.

Asked if Russia needed to introduce a new compulsory mobilisation, Putin said that 1,000 - 1,500 Russians were signing voluntary contracts to join the military every day.

Over the past six or seven months, 270,000 people had signed voluntary contracts, Putin said - a figure slightly lower than the 280,000 that former president Dmitry Medvedev stated earlier this month.