TEHRAN (FNA)- A group in Nigeria renewed its demand for the unconditional release of prominent Shia cleric Sheikh Ibrahim Zakzaky from detention.

The group, Save Zakzaky�s Life, issued on Tuesday a seven-day ultimatum to the government of President Muhammadu Buhari to release Zakzaky, who is the leader of Islamic Movement of Nigeria (IMN), press tv reported.

The group also warned that if the government fails to meet their demand, they will have no other alternative but to call on millions of his followers to take to the streets. It said the sheikh�s supporters will also stage a sit-in until he is released.

The National coordinator of the group, Bashir Marafa, said they have already begun mobilizing millions of Zakzaky�s followers �to storm [the capital,] Abuja, for what we called �MOTHER OF ALL PROTESTS,� and �SIT AROUND IN ABUJA CITY,� as long as Zakzaky is not released unconditionally, within the next 7 days.�

The cleric�s followers are concerned about his health condition, which has been deteriorating over the past nine months in detention. He has been detained since December 13, 2015, when Nigerian forces raided his home and killed three of his sons as well as his wife.

A day earlier, soldiers had attacked Shia Muslims attending a ceremony at a religious center in the city of Zaria in north-central Nigeria, accusing them of blocking the convoy of the army�s chief of staff and attempting to assassinate him, which they denied.

They killed hundreds of members of the religious community. Some sources have put the toll at over 1,000.

Zakzaky had lost three other sons in the summer of 2014 during attacks by Nigerian soldiers on the International Quds day.

Save Zakzaky�s Life had last week issued a 14-day ultimatum for his release. Thousands of his followers also held a peaceful mass protest last week in the capital. Many of the protesters were injured after police attacked the demonstrators and fired tear gas to disperse them.

By Fars News Agency