The main opposition party in Tanzania's Zanzibar Islands (CUF) called for a boycott to the re-run disputed presidential, parliamentary and municipal elections of March 20, on the Indian Ocean archipelago
The electoral body in Zanzibar cancelled previous elections on October 25, due to fraud.
The opposition Civic United Front (CUF) said that it won those elections and has warned of violence on the islands if the rescheduled ballot goes ahead.
"The Civic United Front [CUF] will not take part in the vote re-run ... because it is illegal. A lawful election has already been conducted [in October]," the party said on Thursday.
The opposition also stated that, rather than a new election, a dialogue to form a government of all parties under its leadership should be held.
"We urge all the people of Zanzibar ... to boycott this unlawful re-run election," it said in a statement.
Tanzania has been among most politically stable nations in Africa. The CCM party has ruled mainland Tanzania for more than five decades.
Zanzibar is a hotbed are for separationists, opposition against central government creates tension. Election results on the islands are usually very close and causes disagreement.
Elections in Zanzibar has always been a two horse race, between CCM and CUF.
In the October elections, Zanzibar's President Ali Mohamed Shein of the ruling CCM party ran against Seif Sharrif Hamad of the CUF party. Smaller parties joining the election, obtain lower returns.