"There can be no justification for the level of blood-letting that has been carried out against the sect, whose crime has been protesting the continued detention of their leader, in spite of different court orders to release him from detention," the statement read.
Afenifere, the pan-Yoruba sociopolitical group, has condemned the killing of members of the Islamic Movement in Nigeria (IMN) during their protest in Abuja.
The group said there was no justification for the use of force by security operatives against the protesters.
More than 40 Shi'ites were confirmed to have been killed during the group's three-day annual 'Arbaeen Symbolic Trek', which ended on Tuesday.
Rising from their monthly meeting held at the residence of its foremost leader, Rebuen Fasonranti, in Akure, the Ondo State capital, the Afenifere leaders observed that the killing of the Shi'ites is a crime against humanity.
Chief Korode Duyile, who read a communique presented by Afenifere leaders after their meeting, called for a probe into the killings.
According to Duyile, the continued detention of the IMN leader, Sheikh Ibraheem El-Zakzakzy, by the Federal Government despite a court order has "further proven disrespect for true justice under the governing All Progressives Congress (APC) led by President Muhammadu Buhari".
The statement read: "There can be no justification for the level of blood-letting that has been carried out against the sect, whose crime has been protesting the continued detention of their leader, in spite of different court orders to release him from detention.
“The act of disobedience of court orders is totally reprehensible and confirms the statement by the US Ambassador to Nigeria that perversion of institutions, which abuse of court orders typifies, is the worst form of corruption.
“We, therefore, call on the Federal Government to release the leader of the Shiites as ordered by different courts and ensure that the security personnel responsible for the mass killings of his supporters are brought to book.
“We must not forget how extra-judicial killing of the founder of Boko Haram turned the group into a massive terror machine which we have been unable to contain and we are opening yet another front."
Afenifere also called for a review of the nation's security machinery in order to guarantee free and fair elections in 2019.
The statement continued: "Just take a look at the abduction and killing of the Agom Adara, a pregnant woman in Ondo State; the Zamfara twins, General Alkali; Leah Sharibu is still in the custody of Boko Haram, among others.
“We have also witnessed how Kaduna State, whose Governor Mallam Nasiru el-Rufai once boasted of paying off criminals, has become virtually ungovernable with the recent Kasuwan Magani massacre that led to the deaths of no fewer than 100 persons and the attendant spill-over crisis.
“We are worried that there has been no coordinated response on the part of the Federal Government to these needless loss of precious lives, just as it continues to ignore calls for the overhaul of the country ‘s security architecture with a restructured polity to guarantee greater security of lives and property."