Mararaba (Nigeria) (AFP) - Human rights campaigners on Wednesday accused Nigeria's security forces of killing dozens by using "horrific" force during a crackdown on protesting supporters of an imprisoned Shiite cleric.
Amnesty International said it had "strong evidence" that police and soldiers used automatic weapons against members of the Islamic Movement of Nigeria (IMN) at marches in and around Abuja.
The group said upwards of 45 people were killed -- six on Saturday and at least 39 on Monday, when some 122 were also injured.
The IMN itself said it had counted 49 dead. The military's official death toll is six.
"We have seen a shocking and unconscionable use of deadly force by soldiers and police against IMN members," said Amnesty's Nigeria director, Osai Ojigho.
"Video footage and eyewitness testimonies consistently show that the Nigerian military dispersed peaceful gatherings by firing live ammunition without warning," she added.
"Those injured were shot in different parts of the body -- head, neck, back, chest, shoulder, legs, arms -- and some of them had multiple gunshot wounds."
Ojigho said the "horrific use of excessive force" was not crowd control but aimed to kill, calling for an independent probe and the prosecution of those responsible.
- 'Wronged and oppressed' -
In Mararaba village, in Nasarawa state 30 kilometres (nearly 20 miles) from central Abuja, mourners gathered in preparation for the burial of 20 victims.
AFP reporters counted the white-shrouded bodies, as IMN members and tearful family members of the deceased gathered to pay their final respects.
"These are the victims the Nigerian Army attacked on Monday at Kugbo security check point on our way to Abuja," said IMN member Abdullahi Mohammad Musa.
The group's spokesman, Ibrahim Musa, said separately that another burial for six people was held in the northern city of Zaria.
"We are feeling bad, we are feeling wronged, we are oppressed," he added.
Nigeria, Africa's largest economy, is almost evenly split between a mostly Muslim north -- which is predominantly Sunni -- and a largely Christian south.
Experts have warned the government that a heavy-handed response to the group risks sparking conflict in a volatile region where poverty is widespread.
The December 2015 clashes that led to Zakzaky's detention saw the army kill more than 300 of his supporters, who were buried in mass graves, according to human rights groups.
Amnesty said it appeared a similar strategy appeared to have been employed against the IMN in the latest protests.
The clashes and the military's use of deadly force against civilians have raised fears that the IMN could become radicalised in the same way as the Islamist group Boko Haram in northeast Nigeria, who were subject to a crackdown in 2009.
The military offensive against the jihadist group is widely accepted as the catalyst for it to take up arms against the government.
In the last nine years, more than 27,000 people have been killed and some two million displaced, while the fighting has triggered a humanitarian crisis in Nigeria's remote northeast.
- Self-defence -
Conflicting death tolls are not unusual in Nigeria and the authorities often play down casualty figures.
Nigeria's army said troops fired on IMN in self-defence.
"They met the soldiers in the call of their duty and the soldiers tried to defend themselves," said defence spokesman John Agim.
On Saturday, the military fired at the IMN procession and accused them of attempting to steal weapons and ammunition, an account the IMN "categorically" denies.
Two days later, IMN and troops clashed again on the outskirts of Abuja.
On Tuesday, Nigerian police fired shots and tear gas at the supporters during another march and arrested 400 IMN members.
Zakzaky is currently facing a culpable homicide charge in connection with the 2015 violence and is in jail despite a court order granting him bail.
The Shiite leader, who is in his mid-sixties, has been at loggerheads with the authorities for years because of his call for an Iranian-style Islamic revolution in Nigeria.