At least one person was killed and several more wounded in Burundi on Thursday in a fresh outbreak of clashes between demonstrators, ruling party militia and police, witnesses said.

A small group of protesters clashed with government supporters, thought to be members of the ruling party's Imbonerakure militia, in the Kinama district of the capital Bujumbura.

Police opened fire on the demonstrators, killing one with a bullet to the head and wounding three others, AFP reporters witnessed.

One suspected Imbonerakure member narrowly survived being lynched after being rescued by the army, and a second pro-government militia member was left seriously wounded after being attacked by protesters.

He was rescued after the army fired in the air to disperse the angry mob trying to kill him, an AFP reporter said.

Tensions remained high in the area, with protesters arming themselves with sticks and batons.

Over a dozen people have been killed and scores wounded since late April, when the ruling CNDD-FDD nominated President Pierre Nkurunziza to stand for re-election, triggering daily protests.

Opposition parties and civil society groups say Nkurunziza's third-term quest violates both the constitution, which limits a president to two terms in office, and the accords that ended a 13-year civil war between Tutsis and Hutus in 2006.

On Wednesday Nkurunziza insisted he would run for a third term, defying international pressure.