WELLINGTON, July 27, 2023 (BSS/AFP) - US Secretary of State Antony Blinken on Thursday pressed African leaders attending a summit with Russia's Vladimir Putin to demand answers about a grain crisis that has propelled poorer nations towards crisis.

Speaking ahead of a Russia-Africa sitdown in Putin's hometown of Saint Petersburg, Blinken insisted African leaders knew rising food costs, grain and fertiliser shortages were a direct result of Putin's war in Ukraine.

Several African leaders including South African President Cyril Ramaphosa are expected to attend the Konstantinovsky Palace summit.

"They know exactly who's to blame for this current situation," Blinken said of the leaders, some of whom have offered tacit support for Moscow or refused to denounce Putin's invasion.

"My expectation would be that Russia will hear this clearly from our African partners," he said, speaking during a visit to New Zealand.

The grain crisis has intensified since Russia withdrew from a deal that allowed Ukraine to export 33 billion tonnes of wheat and other grains.

"It was the equivalent of exporting 18 billion loaves of bread through this one corridor that Russia has now shut down," Blinken said.

"It wasn't only pulling out. What have they done since they pulled out? They've repeatedly bombed the port of Odesa. They've laid mines in the Black Sea. They've explicitly threatened shipping. I think that sends a very clear message."

Russia has said the Turkish-brokered deal did not meet a promise of facilitating Russian exports.

In the last few days, Moscow has sought to reassure African partners, saying it understands their "concern" on the issue.

The Kremlin has said that "without any doubt" it is ready to export grain for free to African countries that need it.

According to the latest monthly report from the US Department of Agriculture, wheat stocks at major exporters are currently at a 10-year low.