Amnesty International says it has documented an alarming escalation in attacks and abductions in northern Nigeria, with more than 1,100 deaths since the beginning of the year.

The rights group says the authorities have left rural communities at the mercy of rampaging gunmen and describes the lack of protection as "utterly shameful".

The research focused on seven states in north-west and north-central Nigeria where the violence does not appear to be linked to the country's jihadist conflict but to banditry and cattle rustling.

The attacks are rooted in decades-long competition over resources between ethnic Fulani herders and farming communities.

Amnesty says the villages worst affected are in the south of Kaduna State, where more than 360 people have been killed since January.