The United Nations food agency's world price index declined again in July, edging further away from record highs hit in March, partly thanks to a deal between Ukraine and Russia lifting a sea blockade that had stopped Ukrainian grain shipments.

The Food and Agriculture Organization's (FAO) food price index, which tracks the most globally traded food commodities, averaged 140.9 points last month versus a revised 154.3 for June. The June figure was previously put at 154.2.

The July index was still 13.1% higher than a year earlier, pushed up by the impact of the invasion of Ukraine, adverse weather and high production and transport costs.

Food prices soared to a record high in March after Russia invaded Ukraine, raising fears that the conflict between two of the world's breadbaskets would spark hunger in countries relying on their exports.

"The decline in food commodity prices from very high levels is welcome, especially when seen from a food access viewpoint," FAO chief economist Maximo Torero said in a statement.

"However, many uncertainties remain," he said, pointing to high fertilizer prices, a "bleak global economic outlook" and currency movements.

A bleak global economic outlook, currency volatility and high fertilizer prices – which can impact future production and farmers’ livelihoods – all pose serious strains for global food security, he said.

The vegetable oil, sugar, dairy, meat and cereal price indices all fell month-on-month in July, with wheat slumping 14.5%, partly due to a deal reached between Ukraine, Russia, Turkey and the United Nations to unblock grains exports from Black Sea ports.

The maize price index fell 10.7% in July, also due in part to the Russia-Ukraine deal as well as increased seasonal availability from key producers Argentina and Brazil, the FAO said.

Three ships carrying a combined 58,041 tons of corn were authorized to leave Ukrainian ports on Friday, the organization arranging the operation said. A first vessel carrying Ukrainian grain set sail from Odessa on Monday.