Nigerian police on Thursday fired live rounds into the air to disperse protesters from a banned Shiite group in the capital Abuja. Heavily armed officers clashed with more than 100 rock-throwing demonstrators from the pro-Iran Islamic Movement in Nigeria (IMN). "We are protesting to commemorate the killing of our members in Zaria four years ago," said Muhammed Bello, a Shiite demonstrator. The army killed 350 IMN Shiites, with many gunned down and burned alive according to rights groups, during a religious procession in the northern Nigeria city in December 2015. The protesters were also demanding the release of their detained leader, Muslim cleric Ibrahim El Zakzaky, who is facing terror charges. He and his wife have been held since the 2015 clash.Bello vowed to continue marching despite a government-imposed ban on the group and IMN demonstrations. "They cannot stop from exercising our rights to free protest," he said.Founded by Zakzaky in the late 1970s and inspired by the Iranian Revolution, the IMN has been at loggerheads with the Nigerian authorities for decades.In July the Nigerian government listed the IMN as a proscribed terror group, banning their activities, yet protests have continued.Waves of clashes with security forces have claimed hundreds of lives in the last year.