Turkish President Recep Tayyip Erdogan said Wednesday he still hoped to host Russia and Ukraine for talks this week on easing a global food crisis caused by blocked Black Sea grain.

Erdogan's comments came less than a day after Russian President Vladimir Putin set an unexpected new condition for resuming the deliveries.

Global food prices are soaring, and millions are facing hunger because of Russia's invasion of Ukraine.

The war is being fought across one of Europe's most fertile regions by two of the world's biggest producers of grain.

Up to 25 million tonnes of wheat and other grain have been blocked in Ukrainian ports by Russian warships and landmines Kyiv has laid to avert a feared amphibious assault.

The first direct talks between the sides' military delegations since March -- attended in Istanbul last week by Turkish and UN officials -- came up with an initial draft for resolving the impasse.

The sides had been expected to meet in Istanbul again this week for a second round of talks that both Turkish and UN officials had hoped could produce a final deal.

But Putin said on Tuesday that Russia would only ease the path for Ukrainian grain exports if the West lifts sanctions on Russia's own shipments.

Erdogan told reporters after meeting Putin on the sidelines of a summit in Tehran that he remained hopeful about an agreement.

"As a result of a technical meeting held in Istanbul last week, an agreement was reached on the main outlines of how this process will work within UN frameworks," Erdogan was quoted as telling Turkish reporters aboard his plane home.

"Now this week, we want this memorandum turned into a written text. We hope that the plan will start being implemented in the coming days."

Neither Russia nor Ukraine have officially confirmed their participation at the proposed second round of Istanbul talks.

Erdogan also did not signal when it might be held.

Putin personally thanked Erdogan on Tuesday for playing a central mediation role in the dispute.

But he later told Russian reporters that the West needed to meet certain conditions "if they sincerely want to improve the situation on the international food markets".

"We will facilitate the export of Ukrainian grain, but we are proceeding from the fact that all restrictions related to possible deliveries for the export of Russian grain will be lifted," he said.

zak/ah