The "spice island” of Zanzibar would seem to have little in common with Somalia, torn by Islamist rebellion, and with Kenya, where a storm is brewing over demands for the touristic coastal strip to secede.But in this historic town, a World Heritage site and perhaps the oldest functioning urban area in east Africa, clouds of teargas have hung over ornate alleyways in recent days as riot police clashed with supporters of an Islamic separatist group."We want our government to have supremacy. We want a supreme Zanzibar,” Sheikh Mselem Ali Mselem, leader of the Uamsho group, told Reuters in the run-up to the violence.Mselem denounced the political leaders of Tanzania and semi-autonomous Zanzibar as "liars, unjust, corrupt” and said Uamsho sought peace - but independence from Tanzanian rule.While few expect Zanzibar to become an autonomous Islamic state or for Kenya’s coastal strip to secede, the simmering anger, particularly among coastal Muslims, is an increasingly painful headache for the secular governments in Nairobi and Dodoma.