A senior Ukrainian military officer says the country's forces are not joining pro-Ukrainian volunteer soldiers fighting inside Russian territory.

In an interview with NHK on Tuesday, Roman Kostenko spoke about two armed groups that claim to have intruded into Russia's Belgorod region and are fighting there.

The groups also say their members include Russians fighting against their own country.

Kostenko said the groups have their own goals. He acknowledged that the military is in partnership with them, but said Kyiv does not want Russian land.

He stressed that the military is focusing on massive counteroffensives.

He said although the Ukrainians have gathered a considerable quantity of weapons, Russian stockpiles are several times bigger.

He indicated that the planned offensives are unlikely to end soon, and continued military aid will be needed.

The interview was held after Ukrainian President Volodymyr Zelenskyy attended the Group of Seven summit in Hiroshima in person.

Kostenko said it was a critically important event because the G7 leaders and those of invited countries such as India realized the need to support Ukraine.