The main opposition party in Zanzibar says its presidential flag bearer has been arrested.

The party, ACT Wazalendo, says Maalim Seif Sharif was arrested this morning as the semi-autonomous Island begun early voting in the general elections.

It said the candidate was arrested while trying to cast his vote.

Early voting is designated for officials from the Zanzibar Electoral Commission, returning officers and security personnel.

Mr Seif has been opposed to the amendment that introduced early voting, claiming it would give room to rigging and malpractices - allegations that are strongly denied by electoral commission.

Police are yet to comment on the alleged arrest.

The island has a history of contested polls.

Police have denied reports of killings in Pemba Island.

Juma Saad Hamis, the assistant commissioner of police in Pemba, told the BBC that police were only forced to use teargas on Monday in their attempt to disperse locals who wanted to invade polling centres.

The opposition is claiming three people were killed and several others injured after police used live ammunition to disperse members of the public.