DAR ES SALAAM Tens of thousands of banner-waving protesters marched through Tanzania's capital on Saturday in an unprecedented show of anger over widely discredited elections on the semiautonomous Zanzibar islands.

Residents and journalists put the crowd of opposition demonstrators at over 50,000, making it one of the largest political marches in the history of the East African country.

Twelve opposition groups jointly staged the march through normally sleepy Dar es Salaam to press for fresh elections following the chaotic October polls on the Indian Ocean islands.

"We Declare the Elections in Zanzibar Null and Void," chanted marchers amid the raucous blare of a brass band.

"EU - USA - Don't Support Election Thugs," read one banner.

Dozens of people are believed to have been killed after clashes erupted on Zanzibar in January between police and opposition supporters demanding a rerun of the disputed polls.

Nearly 2,000 Zanzibaris fled to neighboring Kenya.

The islands have been in political turmoil since 1995 when the main opposition Civic United Front (CUF) rejected a narrow election victory by the ruling Chama Cha Mapinduzi (CCM), saying those polls were rigged.

The CUF, which has its stronghold on Zanzibar, again rejected last October's elections and demanded a new poll.

Western observers agreed October's polls were not fair and suspended aid to Zanzibar as a result.

"We want our rights because we are very oppressed," said protester Ayubu Abdullah, 30, who held a placard saying "Rerun the Zanzibar Elections".

"If the elections in Zanzibar had been free we would have won the elections," added Abdullah.

Twelve opposition leaders including CUF Chairman Ibrahim Lipumba led the protest.

The Zanzibar islands joined with mainland Tanganyika in 1964 to form Tanzania, but still enjoy a large degree of autonomy, with their own president and Parliament as well as representation within the Union Parliament.

On Friday 16 opposition MPs were expelled from Parliament in Zanzibar, a day after their colleagues were thrown out of the mainland Parliament.

The Speaker of Zanzibar's Parliament, Pandu Kificho, declared the 16 seats held by the CUF vacant after the MPs boycotted the House for three consecutive sessions in protest at the polls.

Fifteen CUF MPs were also expelled from the Parliament on Mainland Tanzania for the same reason on Thursday.

(Reuter)