By Drazen Jorgic and Fumbuka Ng'wanakilala
STONE TOWN/DAR ES SALAAM (Reuters) - 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.
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. The group demands that police guarantee Hadi's safety.
"We are waiting until tomorrow at 4 o'clock. That will be our deadline. If Farid is not found, we will know what to do," Sheikh Azzan Hamdan told reporters on the steps of Farid's home next to the Mbuyuni mosque.
Hamdan did not say what actions Uamsho would take.
Police "are not doing anything to find Farid ... they are not serious", Hamdan told worshippers, who shouted: "We want our Farid" after leaving the mosque.
Violence between Uamsho and police broke out earlier this year on the archipelago, a tourist hotspot.
"The most important thing now is to find Farid. It will help everyone and bring back peace," a Stone Town street vendor said, declining to give his name out of fear of reprisals.
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.
(Writing by Yara Bayoumy in Nairobi; editing by Andrew Roche)