Russian forces have advanced 1.5 kilometres near the town of Lyman in eastern Ukraine after repelling a Ukrainian attack in the area, Russian Defence Minister Sergei Shoigu said on Tuesday.

"Russian units launched a counterattack, advancing 1.5 kilometres (0.9 miles) along two kilometres of the front," Shoigu said on Russian state television.

But he said Ukrainian forces were still "trying to break through our defences in various areas", adding that in the past two days there had been "several waves of attacks".

On Ukraine's counteroffensive, which began last month, he said that "the enemy has not achieved its aims in any area".

Shoigu also said that a US decision to provide Ukraine with cluster munitions would "naturally have the effect of prolonging the conflict" and Russian forces were taking "additional measures" to defend themselves from this weapon.

But he also boasted that Russian cluster munitions were better, saying: "Russia has cluster munitions that are, let's say, good for all seasons. They are much more effective than the American ones".