WASHINGTON — Global prices for meats, dairy products and cereals resumed rising last month, the United Nations Food and Agriculture Organization reported Thursday, adding to concerns that developing countries may face food shortages.

The agency said that on average, prices rose 1.4 percent in September, after remaining steady in July and August. Scorching heat and drought in the United States, Russia and Europe constricted agricultural production and pushed up prices of corn and soybeans to record highs, the report said.

The largest increases were for dairy products, which rose 7 percent in September, their sharpest climb since January 2011. Higher feed costs were a major factor in the increase, and also helped to drive meat prices up 2.1 percent, especially in the “grain intensive” pork and poultry industries, the report said.

Cereal prices rose 1 percent, and the food agency forecast a decline in global cereal production this year.