Tanzania's semi-autonomous islands of Zanzibar could fail to achieve the millennium development goals because of high population increase, according to the islands' finance minister Mwinyihaji Makame Mwadini.

He said the Zanzibar government was planning to step up its family planning campaign and impose stricter migration rules to regulate the flow of outsiders wishing to settle in the islands.

Opposition politicians have expressed concern over what they claimed were large numbers of people from mainland Tanzania settling in Zanzibar. The leader of the opposition in parliament, Abubakar Khamis Bakari, has advised the Zanzibar government to reintroduce entry permits for mainlanders coming to the islands.

"We have to strengthen the family planning campaign and consider the idea of regulating people coming from outside to settle in Zanzibar. The use of identity cards is also intended to monitor [the entry of] people," Mwadini told Zanzibar's House of Representatives on 10 July.

Members of the islands' parliament had wanted to know what measures the government would take to control the population increase at a time of rising unemployment and land scarcity in Zanzibar.

Zanzibar’s population is estimated at just over a million and is growing at an annual rate of 3.1 percent. The islands registered a population growth of 3 percent between 1978 and 1988, up from 2.86 percent between 1976 and the 1978 census, and 1.81 percent between 1957 and 1967.

Zanzibar is made up of the main islands, Unguja, which covers 1,651 sqkm, and Pemba, the smaller isle of 980 sqkm.