BUJUMBURA (Reuters) - Burundi’s inflation fell to 5.5 percent in the year to September from 5.9 percent in August, as food costs rose more slowly in the landlocked nation, official data showed on Tuesday. Food price inflation was 2.4 percent in the year to September from 3.1 percent to August, the Institute of Economic Studies and Statistics (ISTEEBU) said in its monthly report. The inflation rate in the coffee and tea exporter had accelerated to 5.9 percent in August from 3.1 percent in July after costs for housing, water and energy rose sharply. The International Monetary Fund has previously said inflation in the central African nation of about 10 million people was declining thanks to moderating international prices of food and fuel and stable monetary conditions. IMF has said Burundi's economy was expected to grow by 4.7 percent this year compared with 4.5 percent in 2013, but uncertainty ahead of the 2015 election amid rising social and political tensions could undermine macroeconomic stability.