BAMAKO (Reuters) - A number of civilians were killed in ethnic violence in central Mali, government and local sources said on Friday, in one of a long series of attacks before a hotly-disputed presidential election this weekend.

FILE PHOTO: U.N. vehicles patrol the street, prior to the presidential election, in Bamako, Mali, July 27, 2018. REUTERS/Luc Gnago/File Photo

One local source put the death toll at 18 while another said the attackers had dumped bodies down a well.

Malians will vote on Sunday in the election contested by President Ibrahim Boubacar Keita and a couple of dozen challengers. But inter-communal violence and jihadist attacks have cast doubt on prospects for a smooth election day.

Clashes erupted on Wednesday between traditional Donzo hunters and Fulani herders near the town of Djenne, killing several civilians, a source at the defense ministry said.

The government did not provide further details of the violence near Djenne, which lies about 400 km (250 miles) northeast of the capital Bamako.

Local sources said Donzos targeted Fulani civilians during a raid on a village.

“They went house-by-house and killed all the men and threw the bodies in a well,” Abdrahamane Diallo, who said he had spoken to members of his family in Djenne, told Reuters.

Abdoul Aziz Diallo, who runs an organization representing the Fulani community, said Donzo militiamen shot dead 18 Fulani men in the village of Somena. This had been in retaliation for an earlier land mine explosion they blamed on the Fulani.

Authorities have repeatedly insisted the vote will go ahead despite the worsening ethnic violence, which has killed almost 300 people this year, according to the United Nations.

Experts, however, fear the violence could discourage turnout, which already tends to be low in Mali.

The country has been in turmoil since Tuareg rebels and loosely allied Islamists took over the north in 2012. French forces intervened the following year but the groups have regrouped, launching attacks across West Africa and inciting tensions between different ethnicities.