Niger has arrested 38 suspects over the deaths of 18 people who were killed in clashes between cattle herders and farmers, a police source said on Wednesday.

The clashes near Bangui, a community in the western Tahoua region, were sparked on Tuesday morning after a herd of cattle wandered into a farmer's field and damaged the cereal crop, a local official who declined to be named said.

Public radio reported Wednesday that "over-excited young farmers armed with knives descended on a town to attack the families (of herders). They burnt 22 homes, killed 18 people -- mostly women, children and the elderly -- of whom seven were burnt alive".

"38 people, mainly farmers, have for now been arrested and detained," said a police officer who requested anonymity.

The arrests were part of an inquiry opened following the clashes, added the officer.

Forty-three people were also injured in the violence, according to the interior ministry, which said the incident had caused a "tragic toll".

The home of Bangui's mayor was also set alight during the attack, according to public radio.

"123 women and children threatened by the angry assailants (have been) put under protection in the local police station," according to the police officer, who added that Bangui was calm Wednesday.

Such clashes are not unusual in drought-hit Niger, where food shortages and scarce water supplies inflame tensions, especially during the harvest, which coincides with the transfer of cattle to pasture.

The clashes come nearly two years after 10 people were killed in the same region in similar clashes between cattle herders and farmers.