Burundi's year-on-year inflation rate rose for the third straight month to 6.3 percent in December from 5.5 percent a month earlier, partly due to higher transport costs, official data showed on Wednesday.

The transport index increased by 4.2 percent over the past twelve months to December, from 1.1 percent in November, Elie Ndiririkirirenza, head of the price index at the Institute of Economic Studies and Statistics (ISTEEBU), told Reuters.

The statistics board said transport costs in December were driven up by high fuel prices. The central African nation's government has revised fuel prices upwards four times since mid 2010.

ISTEEBU said it forecast increases in the costs of essential commodities would drive up consumer prices in the land-locked nation this year, although by how much will largely depend on the price of oil on global markets.

The International Monetary Fund expects Burundi's 2011 inflation rate will tip 8 percent. The annual inflation rate in the coffee producing nation of 8 million people fell to 10.5 percent in 2009, from 24.5 percent in 2008, helped by a decline in fuel and food costs.

IMF projects Burundi's economy to grow by 4.5 percent in 2011, from 3.9 percent in 2010.