(CNN) -- Nigeria's security forces have been guilty of serious human rights abuses in their efforts to crack down on the militant Islamist group Boko Haram, Amnesty International said Thursday in a new report. The report paints an ugly picture of spiraling violence, where brutal attacks carried out by Boko Haram, often against civilians, are countered by the security forces with abuses that only add to the problem, the rights group said. Read more about Boko Haram on CNN's Security Clearance blog Boko Haram has become increasingly sophisticated in its methods in the past three years, the report said, carrying out deadly attacks across northern and central Nigeria.
@highlight
NEW: Nigeria's military denies abuses, says rights group allegations are unfounded
@highlight
Rights group: Nigeria's security forces are committing abuses as they combat militants
@highlight
Amnesty International says the government must do more to protect the public
@highlight
Boko Haram militants have killed hundreds in attacks on civilian targets and police
"We sincerely disagree with the report released by @placeholder," he said.