The Islamic Movement in Nigeria (IMN) says 42 of its members have been killed by Nigerian security forces during protests in the capital Abuja over the past two days.

IMN supporters have taken to the streets over the past two days to demand the government release their imprisoned leader Sheikh Ibrahim Zakzaky.

The number of fatalities caused by Nigerian fire previously stood at 25.

Nigerian army troops opened fire at protesters on the outskirts of Abuja on Monday. The police shot at marchers in the city center on Tuesday.

"The death toll of yesterday's attack on our members has risen to seven as of now," IMN spokesman Ibrahim Musa said Wednesday.

"They died as a result of the injuries they sustained yesterday. And the number of those killed on Monday at Maraba (an area on Abuja's outskirts) has also risen to 35," he added.

Nigeria’s crackdown on IMN followers began in December 2015, when the army attacked a religious ceremony in the city of Zaria in northern Nigeria. Nigerian forces later raided Zakzaky's house and arrested him after killing those attempting to protect the prominent Muslim cleric.

A Federal High Court had ordered Zakzaky’s unconditional release in 2016, but the Nigerian government has so far refused to abide by the ruling.

A spokesman for the movement stated back in March that the government in Abuja was planning to indefinitely hold the cleric and his wife in custody.