After two days of violent encounters between the Shiite members of the Islamic Movement in Nigeria (IMN) and the Nigerian Police, the group has accused the police of "holding on to 15 corpses of its supporters slain during the bloody clashes."
It also called on the federal government to free its leader, Ibraheem Zakzaky, so he can receive medical attention.
In a press release on Thursday, the group blamed the security agencies for the downturn in the chain of events which recorded at least 13 casualties, many injured and properties worth millions of naira damaged.
Abdulhamid Zaria, Chairman Shuhada Foundation of the movement, cautioned the security agencies against any "attempt to label them as a terrorist group".
Mr Zaria also said the "police force is holding on to 15 corpses of supporters of the Islamic Movement it killed on Monday while Islamic funeral rites were performed on six of those known to us killed by the police on Tuesday.
"As of now, 15 are seriously injured people, some of whom we took to Abuja University teaching hospital Gwagwalada, but the police 'snatched' them by force on Monday 22/07/19, they are languishing in the detention Centre of SARS, in Abbatoir Abuja, without any medical care.
"Among them are five women needing urgent medical attention. There is a ten-year-old boy in the detention facility, even though he has a bullet wound on his leg. In fact, we learnt that two of the injured died yesterday because of their injuries. We demand that the authorities of SARS give us access to the wounded so that we can attend to their medical needs," the statement added.
"The security agencies are working hard to portray the Islamic Movement in Nigeria as a terrorist organisation. That is why they have started killing people in our name including our supporters. We decry such shameless play with people's lives with reckless abandon."
He also registered his disappointment in those he describes as "hawks" in President Muhammadu Buhari led administration "who are unjustly detaining Zakzaky despite being granted bail by Federal High Court."
"We urge the international community and well-meaning Nigerians to mount pressure on the federal government to release our leader, who is in dire need of urgent medical attention abroad."
PREMIUM TIMES sought the reactions of the FCT command spokesperson, Anjuguri Manza, on the allegation levelled against the police.
He declined comments.
However, the Force spokesperson, Frank Mba, told PREMIUM TIMES via the phone that "he does not know if corpses of 15 Shiite members are in their custody as alleged by the group but will find out".
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"I don't know about it. I have issued a press statement on what I know but I can find out if you can call me in an hour time later."
PREMIUM TIMES called back as requested by Mr Mba. He did not pick the calls or respond to a subsequent text message.
A Shiite protest turned violent on Monday and was the major issue of discussion at a meeting between President Buhari and Inspector-General of Police, Mohammed Adamu.
At least 12 people, including a police officer and a journalist, were killed and several injured when the protesters clashed with security officers.
Amnesty International in a statement said it got a report that "six people were shot dead amid a reckless use of lethal force by the Nigerian police" during the protest.
The Shiite group, IMN, in a statement said 11 of its members were killed during the protest.
The Shiites are demanding the release of their leader, Ibraheem El-Zakzaky, who has been in detention for alleged murder since December 2015.
Mr El-Zakzaky was taken into custody with his wife after soldiers massacred hundreds of his followers in Zaria, Kaduna State, between December 12 and 15.
Mr El-Zakzaky's children were among those killed.
A judicial panel set up by the Kaduna State Governor, Nasir El-Rufai, found the military culpable in the massacre, recommending a major-general and other officers for trial.
No soldier has been arraigned for the massacre of members of the group.
However, Mr El-Zakzaky and his wife Zeenah are being prosecuted for the death of one soldier during the December 2015 incident.
The International Criminal Court is currently investigating the 2015 massacre -- which has an official estimate of 347 deaths. Shiites insist over 1,000 members were killed by Nigerian soldiers during the December 2015 killings.
Since then, dozens of Shiites have been killed by security operatives in protests in Abuja and Kaduna. Many police officers have also been injured with at least one killed. The police accused the Shiites of engaging in violent protests, a charge the Shiites denied.
The Shiites major demand is the release of Mr El-Zakzaky and his wife, Zeenah.