WASHINGTON Russia's withdrawal from a deal that had allowed Ukraine to export its badly needed grain has sparked volatility in grain prices, the White House said on Thursday.

Press secretary Karine Jean-Pierre told reporters that the Black Sea grain initiatives have resulted in more than 32 million tons of grain being exported to rural markets.

"Russia's actions to take such a significant amount of food products off the world markets will exacerbate hunger in some of the hardest-hit areas of the world, including Africa," she said.

(Reporting by Andrea Shalal and Steve Holland; editing by Jonathan Oatis)