Bujumbura - Four people were killed and some 30 wounded in a series of grenade attacks in Burundi, one week ahead of key parliamentary elections, police said Monday.
"It is clear that all these grenade attacks are related to each other, this is a terror campaign organised by opponents of the third term of President Pierre Nkurunziza, to destabilize and try to prevent the elections," a senior police officer said.
The troubled central African nation has been in crisis since late April over Nkurunziza's controversial bid to stand for a third consecutive five-year term, a move branded by opponents as unconstitutional and a violation of a 2006 peace deal that ended 13 years of civil war.
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Parliamentary elections are planned for June 29, ahead of the presidential vote on July 15.
The grenade blasts, which took place overnight on Sunday to Monday, were the latest in a string of attacks. Overnight on Friday, 11 police officers were wounded in a series of explosions.
The most serious attack was in the northern town of Ngozi, when a grenade was hurled into a bar, killing four and wounding 25 others, 10 of them seriously, a police officer said, adding that three suspects had been arrested.
In the neighbouring northern Kirundo province, another person was wounded in a blast, while a grenade was also thrown into a bar in the north-eastern Muyinga district, although no one was hurt in that attack.
"These people want to frighten the population to prevent them from voting," said Muyinga district governor, Aline Manirabarusha.
Last week, the Burundian human rights group Aprodeh said at least 70 people have been killed, 500 wounded and more than 1 000 jailed since late April, when the opposition took to the streets to protest Nkurunziza's bid to remain in power.
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More than 100 000 people have fled the violence to neighbouring countries.
Nkurunziza survived a coup attempt last month and has since faced down international pressure, including aid cuts, aimed at forcing him to reconsider his attempt to stay in power, which diplomats fear could plunge the country back into war.
Police routinely accuse anti-government protesters of the attacks, while the protest leaders blame security forces "seeking a pretext to justify their excessive use of force and live ammunition".