ZANZIBAR, Tanzania (AP) — An opposition party in the island archipelago of Zanzibar declared victory in a presidential election here even as official tallying continues, raising tensions as mainland Tanzania awaits official poll results.

Maalim Seif Hamad of the Civic United Front party announced Monday that he had won the Zanzibar presidential election, saying he beat his rival, Ali Mohamed Shein of Tanzania's ruling party, with more than 52 percent of the vote.

"Our supporters know we have won. They have gathered to celebrate. They have been extremely patient and it would be counterproductive to attempt to trick them out of their moment," he said in a statement. "For those who have still not come to grips with this reality, and still think there are ways of fabricating a different outcome, we would like you to know that it is over."

He urged Tanzanian President Jakaya Kikwete "to facilitate a smooth transition and not to allow Zanzibar to descend into chaos."

Police fired tear gas to disperse Hamad's supporters who had gathered to celebrate here and on the island of Pemba.

Although part of Tanzania, Zanzibar is run by a semi-autonomous government with its own president.

Full results from Tanzania's largely peaceful presidential election, widely seen as the most tightly contested in the nation's history, are expected on Thursday.

The ruling party's candidate, Works Minister John Magufuli, is battling former Prime Minister Edward Lowassa, who defected to the opposition earlier this year after being rejected as the ruling party's candidate.