Nigeria's Boko Haram Islamists on Tuesday claimed a weekend attack at a graveyard in central Plateau state that killed at least 22 people, but police insisted another group was responsible.
After the raid that also left two prominent politicians dead, officials and police blamed Fulani herdsmen, a majority Muslim group with long-standing land rights grievances against the state's mainly Christian leaders.
Boko Haram has in the past claimed killings widely thought to have been carried out by another group, in an effort to boost its stature.
In a statement issued from purported spokesman Abul Qaqa, Boko Haram said it "wants to inform the world of its delight over the success of the attacks we launched... in Plateau state on Christians and security operatives, including members of the National Assembly".
Among those killed in the graveyard assault were federal senator Gyang Dantong and the majority leader of Plateau state's legislature Gyang Fulani, both said to be Christian.
"We will continue to hunt for government officials wherever they are; they will have no peace again," said the statement from the Islamist group that has carried out waves of assaults in northern and central Nigeria.
Boko Haram has also previously struck in Plateau, including a suicide bombing at a church in the capital Jos last month.
But a police source in Plateau, who requested anonymity, told AFP on Tuesday that "if Boko Haram were involved, it is because the Fulani invited them to take part".
"Suspected Fulani are the ones that carried out that attack. That is the opinion of police," said the source.
Fulani pastoralists, of Hausa-Muslim ethnicity, are seen as "settlers" by the Christian ethnic groups that dominate power in Plateau state, even though the Fulani have been there for decades.
Policies that favour indigenous Christian groups when it comes to such issues as patronage, jobs and land have created animosity, and sparked flashes of violence, some of it directed against the Fulani themselves.
The funeral where the Sunday killings took place was for some of those killed in an attack the previous day.
Officials said that suspected Fulani gunmen stormed several Christian villages in Plateau on Saturday, killing at least 80 people.
In January, Boko Haram claimed the murder of 17 Christian traders in the northeastern Adamawa state, which police later concluded was the result of an inter-communal conflict.
The Islamist group has killed more than 1,000 people since mid-2009 in Africa's most populous nation and top oil producer.
Plateau state falls in Nigeria's so-called "Middle Belt," where the mainly Christian south meets the majority Muslim north, and has been the site of waves of sectarian violence in recent years.