Ushakov told Russian media that 17 African heads of state would speak at the Russia-Africa summit, which takes place on Thursday and Friday, the agencies said.
He also said South African President Cyril Ramaphosa, who "plays a crucial role in advancing the Africans' initiatives," would hold a bilateral meeting with Putin the day after the multilateral summit, on Saturday.
Last month, Ramaphosa visited Putin in St Petersburg with leaders from Senegal, Egypt, Zambia, Uganda, the Republic of Congo and the Comoros to present a peace plan for Ukraine.
But Putin gave the leaders a list of reasons why he believed many of their proposals were misguided, pouring cold water on a plan already largely dismissed by Ukraine.
Since then, African leaders' fears about the war have become more urgent.
Last week, Russia quit a deal allowing Ukraine, one of the world's leading grain exporters alongside Russia, to ship grain safely out of its ports on the Black Sea despite the war.
The resulting shock to world grain prices has been exacerbated by Russian attacks on those seaports and on the Ukrainian ports on the River Danube that have been taking up some of the slack, threatening to cause shortages in parts of Africa that depend on imported grain.
United Nations Secretary-General Antonio Guterres said it was "especially devastating for vulnerable countries struggling to feed their people".
Russia has suggested that it can help Africa with both commercial and free shipments of Russian grain.
Meanwhile, Ukrainian forces say they have made some gains in eastern and southern Ukraine but are also facing problems.
"Due to the difficult and contradictory situation in the Bakhmut and Lyman sections, we have had to adjust our plans," the commander-in-chief of the land forces, Oleksander Syrskyi, announced on Telegram on Tuesday.
Earlier, General Staff spokesman Andrey Kovalev reported an advance towards the village of Andriivka south of the Russian-controlled town of Bakhmut.
In the southern part of the Donetsk region, Ukrainian troops had again advanced between 500 and 750 metres near the village of Staromajorske.
The Ukrainian changes in plans are presumably related to Russian advances from the Luhansk region towards the neighbouring Kharkiv region north of the Ukrainian-controlled town of Lyman.
According to consistent reports, Russian troops have made gains west of Karmazynivka, which is southeast of Kharkiv.
with DPA
