Global food prices have risen to record high levels since Russia’s invasion of Ukraine, prompting protests in developing countries.

The Black Sea port in Ukraine, the world’s fourth largest grain exporter, has been blocked since the invasion, and about 20 million tonnes of grain are currently stuck in the country.

Ms Prentiss, speaking at an International Grain Council (ICC) conference in London, said she had heard for the first time allegations of Russia stealing grain from sources in the Kherson region of southern Ukraine.

Russia has previously denied allegations of wheat theft in Ukraine.

The United Nations is trying to strike a deal to allow Ukrainian grain to be shipped from Black Sea ports such as Odessa, while Russia has said it wants Western sanctions lifted as part of a deal.

Ukraine and the West accused Moscow of weaponizing the food supply. Russia attributes this situation to Ukrainian mines in the waters of the Black Sea and international sanctions against its economy.

Last week, Ukraine said Russia was sending stolen grain to Turkey from Crimea, which it captured in 2014. It also accused Russia of sending 100,000 tons of stolen Ukrainian wheat to its ally Syria.