* Attacks bear hallmarks of FNL rebels
* Burundi authorities blame killings on bandits
* Whereabouts of FNL rebel leaders unknown
By Sadi Niyungeko
BUJUMBURA, Sept 24 (Reuters) - A series of macabre civilian murders in Burundi is threatening the central African nation's fragile political stability, and has raised fears that a new rebellion might be brewing.
The government blames bandits, but some central Africa analysts say the attacks bear the hallmarks of the former Forces for National Liberation (FNL) rebel group.
"It is clear those bandits are located in an area that is a well known area for FNL," said Thierry Vircoulon, central Africa project director at International Crisis Group (ICG). "They operate in the same way the FNL used to operate. They have targeted the people and animals of their enemies."
Former FNL rebel leader Agathon Rwasa disappeared from Bujumbura in late June after boycotting presidential elections which he said would be rigged. Rwasa and a number of close allies were said to have moved to South Kivu in neighbouring Democratic Republic of Congo.
Vircoulon said the attacks were worrying for Burundi's political stability, and underscored tensions after it held a number of elections that most opposition parties boycotted.
"It is worrying of course... given the history of the country and you can see the same patterns of actions, actions targeting civilians."
Burundi's population of 8 million people has a turbulent post-independence history. Bitter divisions between the Tutsi and Hutu ethnic groups fanned years of civil war.
In one attack earlier this month, gunmen killed at least seven workers on a sugar plantation in the Rukoko forest, 25 km outside Bujumbura. The assailants returned later to slaughter dozens of cattle.
Sugar worker Esperance Ndayisenga told Reuters one attacker was dressed in military fatigues while another wore a police uniform, and both brandished guns that she said appeared new.
A few days later, at least a dozen corpses, some of them bloated and badly mutilated, were found in the marshy banks of the Rusizi river
Burundi's newly formed government insists the rebels have not regrouped and police said they had arrested 22 "wrongdoers", including two responsible for the Rukoko forest murders.
Simeon Barumwete, a political analyst at the University of Burundi, said the killers' style was not typical of thieves.
"They use ambush. They kill people and take nothing from them. They rob households in order to have food for their livelihoods. That's how the former rebellions also started in Burundi," Barumwete said.
The FNL Hutu guerrilla group signed a truce in 2005 to end more than a decade of civil conflict, before laying down its weapons and joining the coalition government last year.
It had been fighting to end years of political dominance by the Tutsi ethnic group in the tiny landlocked nation. During the implementation of the peace deal, FNL insisted on the political name "palipehutu", which means party for the liberation of Hutus. (Additional reporting and writing by Richard Lough in Nairobi; Editing by James Macharia/David Stamp)
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