The embattled nation's year-end inflation rate, however, hit 11.6 percent, up from 7.6 percent last year, the Census and Statistics department said.
"This satisfactory growth rate of 6.4 percent in GDP (gross domestic product) for the third quarter of the year 2005 ... was achieved due to ... (the) continuation of (the) peaceful environment created in the country," the department said in a statement.
The growth figure covered the three-month period to September, before clashes between government forces and suspected Tamil Tiger rebels intensified this month leaving at least 83 people dead despite a truce that has been in place since February 2002. Sri Lanka's Central Bank said meanwhile that the adverse effects of the December 2004 tsunami, which killed some 31,000 people and left a million homeless, continued to be felt in the fishing, hotel and restaurant sectors.