Leading rights group Amnesty International has called on the Nigerian authorities to address the rising insecurity in the country, after it said more than 1,800 had been killed since January.

The group said the killings were the result of conflict between herders and farmers, communal clashes, the Boko Haram insurgency and banditry.

Opposition People's Democratic Party publicity secretary Kola Ologbondiyan said Nigeria was turning into a "funeral parlour" under President Muhammadu Buhari's leadership, and he needed to be voted out in next year's election.

Last weekend, at least 86 people were killed in Plateau state, where well-armed nomadic cattle herders attacked several farming villages.

Amnesty says the attackers, often in their hundreds, spend hours at the scene without any intervention from the security forces.

In a statement on Thursday, Mr Buhari said that despite the security challenges, the government has had "notable successes" in tackling insecurity.