World food prices rose 2.3 percent in July from the month before, their third successive monthly increase, supported by higher values for most cereals, sugar and dairy, the United Nations food agency said on Thursday.

The Food and Agriculture Organization's (FAO) food price index, which measures monthly changes for a basket of cereals, oilseeds, dairy products, meat and sugar, averaged 179.1 points in July, its highest since January 2015.

Food on international markets was 10.2 percent more expensive than in the same month last year, with higher prices mainly supported by supply constraints and currency movements.

Vegetable oil prices fell 1.1 percent to hit their lowest since August 2016, dragged down by palm oil, which is facing a combination of good production prospects and weak global import demand.