By Fumbuka Ng'wanakilala
ZANZIBAR (Reuters) - Tanzania's semi-autonomous Zanzibar archipelago went to the polls on Sunday amid tight security in a re-run of disputed elections that have been boycotted by the main opposition party.
Zanzibar's electoral authority annulled a previous ballot on Oct. 25 on grounds of fraud. The opposition Civic United Front (CUF) says it won those elections and it had warned of violence on the Indian Ocean islands if Sunday's ballot went ahead.
Polling stations closed at 4 p.m. (1300 GMT) and election officials started counting the vote, a Reuters reporter said.
Zanzibar President Ali Mohamed Shein, who won in 2010 on the ruling Chama Cha Mapinduzi (CCM) party ticket with 50.1 percent of the vote, expressed confidence about the outcome.
"I expect to win with a landslide victory," he told reporters after casting his ballot.
The CUF urged its supporters to boycott the presidential, parliamentary and municipal elections in a move that could mean a shoo-in for the ruling CCM party.
CUF leader Seif Sharif Hamad, who opted to remain in Dar es Salaam while the elections were conducted in Zanzibar, said whoever is declared the winner of the re-run polls would lack legitimacy to rule the archipelago.
"Zanzibar will likely experience violence in the coming future after enjoying peace and tranquillity over the past five years," Hamad told reporters.
Other smaller opposition parties are taking part in the vote, but elections in Zanzibar are usually tight two-horse races between the CCM and CUF.
Security was tight around polling stations. Zanzibar elections have previously been marred by violence.
President Shein said the repeat elections were peaceful.
Asked to comment on the opposition CUF's decision not to take part in the polls, he said: "It's their decision ... they decided to boycott the elections. We have nothing to say."
Zanzibar authorities temporarily banned passenger ferry services between the semi-autonomous islands and mainland Tanzania on Sunday, in what officials said was a move aimed at making sure there were no disruptions to voting.
Zanzibar was rocked by post-election violence in 2001, resulting in the death of more than 35 people.
Shein stood in the previous polls against his main challenger, the CUF's Hamad, who has lost four elections since 1995 by narrow margins.
The Zanzibar Electoral Commission said there are around 500,000 registered voters, with final results expected to be announced within three days.
(Reporting by Fumbuka Ng'wanakilala; Editing by George Obulutsa and Stephen Powell)