Lagos - The country's top human rights body on Monday said that eight people shot dead by intelligence agents in Abuja last year were civilians and not Boko Haram militants, as the government claimed.
The Directorate for State Services (DSS) said on September 20 last year that it uncovered an Islamist plot to attack a residential building used by federal lawmakers.
According to the DSS account, which was immediately questioned, seven Boko Haram fighters died in a gun battle with agents at the scene, while another suspected militant fighter died later.
But the National Human Rights Commission said in a new report into the shootings: "No evidence has been offered to warrant or support labelling any of the victims to be members of... Boko Haram.
"The Commission declares that not being members of (Boko Haram), the victims were not combatants and were entitled to protection as civilian non-combatants," it added.
The 85-page report recommended that Nigeria pay each of the victim's families 10 million naira, ($60,000, 45,000 euros), while five million naira should go to the 11 surviving victims.
The commission's reports are not legally binding but have been used in the past to support successful civil cases against the government.
Hours after the DSS released details of its reported clash with Boko Haram in the heart of the capital, media reports suggested that in fact the officers had been sent to clear squatters from a property owned by a prominent military figure.
Boko Haram had attacked Abuja before, notably in the August 2011 bombing of a United Nations building.
But, the DSS claim that waves of Islamist gunmen had opened fire on intelligence officers outside a prominent government building raised fears that Nigeria had completely lost control of an insurgency which has killed thousands since 2009.
Questioned about the report days later, President Goodluck Jonathan insisted DSS officers had clashed with Boko Haram.
The commission's report found that more than 100 people were squatting in a building next to the lawmakers' residence and that there was no evidence to suggest they initiated violence against DSS officers.
"The defence of self-defence asserted by the (DSS) is not supported by the facts or evidence," the report reads.
"The application of lethal force was disproportionate and the killings of the eight deceased persons as well as the injuries to the eleven survivors were unlawful."