Zanzibar first Vice President Seif Sharif Hamad has died at the age of 77.
Tanzania president John Magufuli sent his condolence message through social media on Wednesday.
"Nimepokea kwa masikitiko taarifa ya kifo cha Maalim Seif Sharif Hamad, aliyekuwa Makamu wa Kwanza wa Rais wa Zanzibar," he said.
He added: "Natoa pole kwa Rais wa Zanzibar Mhe. Dkt. Mwinyi, Familia, Wazanzibari, wanachama wa ACT-Wazalendo na Watanzania wote. Mungu amweke mahali pema peponi,Amina."
Ndugu wananchi wa Zanzibar na Watanzania kwa ujumla, Kwa masikitiko makubwa nakujulisheni leo tarehe 17 Febuari, 2021 majira ya saa 5:26 Asubuhi Makamu wa Kwanza wa Rais Maalim Seif Sharif Hamad amefariki dunia. Maalim amefariki wakati akiendelea na matibabu.
— Dr Hussein Ali Mwinyi (@DrHmwinyi) February 17, 2021
UK commissioner to Tanzania David Concar also sent his condolences.
"Saddened by news of the death of Maalim Seif Sharif Hamad, a giant of Zanzibar politics who will be greatly missed," Concar tweeted.
"He leaves a towering legacy of service, commitment and passion for improving lives. My condolences to his family and the people of Zanzibar. Upumzike kwa amani."
He became the first person in Tanzania to publicly reveal a Covid-19 status since April last year when Magufuli declared the country coronavirus-free.