Dar es Salaam - Opposition leaders in Zanzibar said on Wednesday they would not take part in celebrations for the inauguration of Tanzania's new president John Pombe Magufuli, after elections were annulled on the islands.
Several African leaders are due on Thursday in the economic capital Dar es Salaam for Magufuli's swearing in, including the African Union chair, Zimbabwean President Robert Mugabe, and regional heads of state.
Ruling party candidate John Magufuli won Tanzania's hotly contested presidential elections with over 58% of votes, cementing the long-running Chama Cha Mapinduzi (CCM) party's firm grip on power.
Samia Suluhu Hassan, who comes from Zanzibar, will become Tanzania's first ever female vice president.
Outgoing Tanzanian President Jakaya Kikwete has declared the day a holiday.
"The decision is aimed at making all Tanzanians participate fully in the ceremony, where Kikwete will be stepping down and Magufuli being sworn-in as the country's fifth president," presidential chief secretary Ombeni Sefue.
But the mood was gloomy on Zanzibar, with opposition supporters on the Indian Ocean archipelago saying they were "unhappy" that Tanzania was pressing ahead with the swearing in ceremony.
Zanzibar's electoral commission ruled last week that the October 25 vote on the islands - where the 500 000 registered voters also cast ballots for Tanzania's national president - must be carried out again, citing "violations" of electoral law.
The annulment came after a key candidate, Seif Sharif Hamad of the opposition Civic United Front (CUF), declared himself the winner before the results were officially announced.
"No one seems to bother about our concern about the disputed cancellation of the elections," said Nassor Ahmed Mazrui, CUF deputy secretary general, saying the mandate of the islands' president had expired, claims the government rejects.
Homemade bombs exploded in Zanzibar town over the weekend. No one was wounded, but the explosions sparked concern on the islands, whose economy is dependent on foreign tourists.