Muslim protesters clashed with police in Tanzania's commercial capital and on the semi-autonomous island of Zanzibar on Friday, raising religious tensions in the east African country.
In Dar es Salaam, protests against the arrest of a hardline Muslim cleric turned violent, while in Zanzibar, supporters of an Islamist separatist group have repeatedly fought police over the disappearance of their spiritual leader, who was then released after nearly four days in captivity.
The violence has raised concerns of an escalation in religious tensions in relatively stable and secular Tanzania, east Africa's second-largest economy.
In Zanzibar, a predominantly Muslim island, supporters of the Islamic Uamsho (Awakening) movement protested for the third day.
Uamsho followers, mostly youths and urban poor, clashed with police after Friday prayers, hurling rocks at police who retaliated with tear gas in sporadic exchanges around the main historic area of Stone Town.
Roads were temporarily closed, with rocks and coconuts strewn across the asphalt, and most businesses shut for the day. Riot police were stationed around mosques around Stone Town.
Fighting erupted on Wednesday, a day after the group's leader Sheikh Farid Hadi disappeared in unknown circumstances.
But late on Friday evening, the popular cleric was released, with shouts of "Allah Akbar" heard rising above Stone Town's maze of narrow alleys which separate Arab-style white coral stone houses.
"He is free. I had my picture taken with him," Thabit Juma, an eyewitness, told Reuters.
One Uamsho member who did not wish to be named confirmed Hadi has been freed, though he would not comment on who was responsible for his disappearance.
Earlier in the day another influential Uamsho cleric Sheikh Azzan Hamdan said the police were not doing enough to search for Hadi and set a deadline, 4pm (1am NZT) on Saturday, for Hadi's safe return.
Violence between Uamsho and police broke out earlier this year on the archipelago, a tourist hotspot.
Analysts say the Uamsho group has been gaining popularity because of disenchantment with Zanzibar's main opposition Civic United Front party after its decision to form a government with the ruling Chama Cha Mapinduzi party.
POLICE ON ALERT
In Dar es Salaam, protesters left the Mtambani mosque after Friday prayers and marched towards the town centre chanting demands for the release of Muslim cleric Sheikh Issa Ponda.
"Police came in and started firing tear gas, while Muslim protesters responded by throwing stones," witness Salum Haji told Reuters. In the city centre streets were deserted in anticipation of further violence.
"All shops are closed in the city centre and there are heavily armed policemen patrolling the streets. We are all locked inside (a shop). I don't know how I'm going to get home," resident Neema Swai told Reuters.
Dar es Salaam's regional police commander, Suleiman Kova, said Ponda had been arrested on Tuesday for criminal trespass on private property and inciting followers to commit violence.
Ponda is the secretary general of the Council of Islamic Organisation, a group that vies for influence against the government-backed National Muslims Council of Tanzania.
Though Ponda is not known to have any links to Uamsho, the protesters also demonstrated against Hadi's disappearance.
Mainland Tanzania, ruled by the secular government of President Jakaya Kikwete, has been rocked by religious tension for the past week.
Muslim protesters burnt five churches on the outskirts of Dar es Salaam on Friday after reports emerged a young Christian boy had urinated on a Koran, Islam's holy book. Local media said the boy had been dared by friends to urinate on the book.
Kikwete visited the torched churches and called for calm.