An amnesty granted to the Sultan of Zanzibar - the monarch who was deposed in a rebellion 36 years ago - has provoked a controversial response on the island.

Sultan Jamshid bin Abdallah bin Khalifa was pardoned on Wednesday, by Zanzibar's President, Salmin Amour, on the anniversary of the 1964 uprising.

The sultan is now in his seventies and lives in exile in the United Kingdom.

Dr Salmin Amour stressed that the monarch was free to return not as a monarch but as an ordinary Zanzibari citizen.

Sultan Jamshid and and the mainly Arab ruling class were deposed in a rebellion led by the island's mainly black African citizens, in which an estimated 10,000 people were killed.

Opposition anger

The Chairman of the opposition United Democratic party (UDP), John Cheyo, has criticised the amnesty and said that 18 detained opposition activists from the Civic United Front should have been released instead.

"These people in custody are suffering a lot, and there is no one to help them because the laws are in favour of the government", he said.

Other Zanzibari oppositions have described the amnesty as "very funny" or "tricky".

But another opposition leader, Mbaraka Shamte, applauded the president's action, saying the amnesty has come at the right time.

Historic political tensions

The sultan first fled to Oman in 1964 and later settled in the UK.

Within three months of his overthrow, the island united with mainland Tanganyika to become present-day Tanzania.

Under the union treaty, Zanzibar's one million population have the freedom to run their own affairs.

But political tensions have left the island deeply divided, the main adversaries being between Dr Amour's ruling Chama Cha Mapinduzi party (CCM), and the opposition CUF.

The dispute began in 1995 after Zanzibar's first multi-party elections, which were won by the CCM.

But the polls were widely believed to have been rigged, and Western aid to Zanzibar was suspended following the 1995 election.