The semi-autonomous islands of Zanzibar have marked the 40-year anniversary of their union with the then-Tanganyika mainland to form Tanzania. Tanzania's president, Benjamin Mkapa, told a packed stadium in Zanzibar that the so-called union government, the legislative and administrative arrangement between mainland Tanzania and the islands known for their tourism, is an example for the rest of the continent to follow.

President Mkapa says Tanzania is one of the few stable countries in Africa, in large part because of the union arrangement between the mainland and the group of islands that make up Zanzibar.

For several-hundred years, Zanzibar was ruled by a succession of Omani sultans who coordinated slave and spice trades along the Indian Ocean.

In January 1964, Zanzibari nationalists, backed by their mainland counterparts, overthrew the sultan in a bloody revolution. Three months later, Zanzibar joined with Tanganyika to form the United Republic of Tanzania.

Under terms of the union government, the mainland is responsible for such areas as defense, immigration, the economy, foreign affairs and internal affairs. The Zanzibar government, which has its own president, has jurisdiction over the islands' education, social, and cultural affairs, among other things.

But some analysts say that while most Zanzibaris agree in principle with the idea of union with the mainland, in practice some arrangements do not benefit Zanzibaris like they benefit mainlanders.

The chief whip of the main opposition party, Civic United Front, Abbas Muhuzi, says taxes set by the mainland government often discriminate against Zanzibaris, whose incomes tend to be less than those found on the mainland.

"So if the mainland says that this [good or service] should be charged 35 percent, and the economy is strong, the people there can pay for that 35 percent," he explained. "Here in Zanzibar, people cannot pay and then we have to follow our brothers there."

Mr. Muhuzi claims the bureaucracy of the two-government structure is cumbersome and causes delays in certain policies being enacted and implemented.

He also says that, if elected in Zanzibar's upcoming 2005 election, his party will ensure Zanzibar has its own flag so that Zanzibaris can have their distinct identity.

Observers say the Zanzibari government is sensitive to criticisms of the union. In his anniversary speech, President Mkapa said those who want to dismantle the union are, in his word, stupid.

The leader of Zanzibar's Council of Imams, Farid Hadi, says he was arrested in March and accused of firebombing a police car during recent violence on the island.

Mr. Hadi told VOA that, once in captivity, officers questioned him constantly about a recent talk he delivered in which he criticized the January 1964 revolution as being bloody and violent.

In his words, the anniversary event was not to be celebrated, but something to be ashamed of because of the events leading up to the union government's formation.