Russian President Vladimir Putin Thursday offered free grain to six African countries as he launched a summit with leaders from the continent days after withdrawing from the Ukraine grain export deal.

The two-day summit in Putin's native Saint Petersburg is being scrutinized as a test of his support in Africa, where he retains backing despite international isolation sparked by the start of the Russia-Ukraine war.

Russia last week refused to extend a deal under which Ukrainian grain exports passed through the Black Sea to reach global markets, including Africa, easing pressure on food prices.

In a keynote address at the summit, Putin said Russia could "substitute Ukrainian grain" and promised to send grain to six African countries.

"In the coming months we will be able to ensure free supplies of 25,000 to 50,000 tonnes of grain to Burkina Faso, Zimbabwe, Mali, Somalia, Central African Republic and Eritrea," Putin said.

Over a year, the grain deal allowed around 33 million tonnes of grain to leave Ukrainian ports, helping to stabilize global food prices and avert shortages.

Since the suspension of the agreement attacks have intensified on the southern Odesa region home to Ukraine's ports -- where the Russian army said it hit military infrastructure