The Black Sea Grain Initiative aimed at easing the global food crisis is set to expire at the end of July 17 unless Russia agrees to its renewal - and Moscow remains unhappy about the operation of a twin agreement that runs alongside the deal.
If it collapses, it would "absolutely hit eastern Africa very, very hard," said Dominique Ferretti, the U.N. World Food Program's senior emergency officer in the region.
"There's a number of countries that depend on Ukraine's wheat. And without it, you would see significantly higher food prices," he told reporters via video-link from Nairobi.
Russia's full-scale invasion of Ukraine in February 2022 saw Ukraine's Black Sea ports blocked by warships until the deal, signed in July, allowed for the safe passage of exports of critical grain supplies.
Ukraine was one of the world's top producers and the grain deal has helped soothe the global food crunch triggered by the conflict.
Some 32.4 million tons have been exported so far under the agreement, according to the U.N. Just over half of the exports have been corn, while more than a quarter were wheat exports.
The initial 120-day agreement struck with the U.N. and Turkey last July was extended for a further 120 days in November, until March 18, then extended again.
The parallel agreement, between Moscow and the U.N., is aimed at facilitating the export of Russian food and fertilisers, which are exempt from Western sanctions imposed on Moscow.
But Russia consistently claims that this parallel agreement is not being upheld.
On June 13, Russia again threatened to pull the plug, believing that certain clauses were still not being respected, despite successive U.N. assurances.