NAIROBI (Reuters) - Burundi's tax revenue fell 17 percent in the last quarter of 2015 compared with the year-ago period, depressed by months of political violence sparked by President Pierre Nkurunziza’s disputed decision to run for a third term.

The aid-dependent central African nation, whose economy relies on coffee and tea exports, is embroiled in one of its worst crises since a civil war ended in 2005. Nine months of strife has killed over 400 people.

The Burundi Revenue Office (OBR) said it collected 157.84 billion francs ($102.16 million) in taxes in the October-to-December period, down from 191.32 billion francs for the same period in 2014, and 38.46 billion francs short of its target.

"Due to the crisis Burundi is going through, the fourth quarter’s results show an underperformance both in forecasts and results,” OBR Commissioner General Domitien Ndihokubwayo told a news conference. "One of the reasons is the security situation which impacted on the Burundi economy.”

Nkurunziza won re-election in July, a vote that was boycotted by most of the Burundian opposition. Opponents said a third term for Nkurunziza violated the constitution. His supporters cited a court ruling that said he could run again.

His return to power raised concerns that there could be another bloody ethnic conflict in a region where memories of neighbouring Rwanda's 1994 genocide remain fresh.

In the latest bout of violence, four people including a child were killed on Saturday night when three grenades exploded in the capital Bujumbura.

The African Union said last week it had appointed five heads of state to try to convince the Nkurunziza government to accept a peacekeeping force that he has rejected.