A local leader of Burundi's ruling party was attacked and killed in the capital Bujumbura, officials said yesterday, the third high-profile attack in three days.

Come Harerimana, president of the CNDD-FDD chapter in Kanyosha district, was heading to his office on the back of a motor bike when a crowd threw stones at him, the officials said.

Harerimana was pulled from the motorcycle and shot.

Burundi is going through its worst political crisis since an ethnically-driven civil war ended in 2005. It began in April when President Pierre Nkurunziza announced he would seek a third term in office, a move his opponents said violated the constitution and a peace deal that ended the war.

Nkurunziza was declared the winner of the July 21 election following months of street protests and a thwarted coup.

On Sunday, Nkurunziza’s former security chief Gen Adolphe Nshimirimana was ambushed and killed and a day later a leading human rights activist, Pierre Claver Mbonimpa, was seriously wounded in a gun attack near his home.

In an address to the nation following the killing of Nshimirimana - who at the time of his death was in charge of the president's personal security – Nkurunziza called for calm and said Burundians must not "fall in the trap of revenge.”

Meanwhile, residents of Cibitoke, a district of Bujumbura that has seen frequent clashes, said gunshots could be heard throughout Tuesday night and early Wednesday and that police had been searching for weapons.

African leaders fear the violence could split the country down ethnic lines and lead to another civil war.