The US has condemned the recent spate of "senseless and? brazen killings" in northern Nigeria.

Dozens of soldiers and civilians were last week killed in twin attacks by Islamist militants in north-eastern Borno state.

Days earlier some 20 people were killed and 20 injured during an attack in north-western state of Katsina by bandits who are often accused of involvement in cattle rustling and kidnapping for ransom.

"The US calls on the government of Nigeria to do more to strengthen ongoing efforts to address this violence, hold those responsible accountable and protect ?civilians," the US embassy said in a statement.

A decade-long insurgency in the north-east by Boko Haram Islamist militants, including a faction that fights under the banner of the Islamic State group, has left thousands of people dead and forced many more from their homes.

Deadly violence related to cattle has been going on for years in Nigeria - even longer than the northern Islamist insurgency and southern oil militancy.