The BBC says the UN uses a broad index of global food costs, which have climbed for 12 months in a row.
Suppliers have been affected by disruptions to production, labour and transport during the pandemic.
Concerns are growing about broader inflation and how higher grocery bills will impact the world’s economic recovery.
The UN Food and Agriculture Organization’s (FAO) food price index tracks prices around the world of a range of food including cereals, oilseeds, dairy products, meat and sugar.
According to the index, food prices in May were 4.8 per cent higher than April – the biggest monthly rise since October 2010 – and 39.7 per cent higher than this time last year.
All five components of the index rose, led by the surging cost of vegetable oils, grain and sugar.
That pushed the index up to its highest overall level since September 2011.