Tanzania's Samia Suluhu Hassan was on Friday sworn in as the country's first female president after the sudden death of John Magufuli from an illness shrouded in mystery.

Fifty-seven people perished in Tanzania on Saturday when a fuel tanker exploded after overturning on a road west of the country's economic capital Dar es Salaam, police said.

The disaster took place near the town of Morogoro, with police saying the blast may have been sparked by a cigarette as people rushed to collect leaking fuel from the stricken truck.

Three people were killed in Tanzania after a group of youths armed with machetes stormed into a mosque slashing those inside, police said Friday.

The attack took place late Thursday in the northern Tanzanian town of Mwanza, on the shores of Lake Victoria.

Newly elected Tanzanian President John Magufuli has scrapped independence day celebrations to spend the money on a clean-up campaign, an official statement said.

"It is so shameful that we are spending huge amounts of money to celebrate 54 years of independence when our people are dying of cholera," Magufuli said in a statement read on state television late Monday.

Zanzibar has formally annulled October's elections meaning a rerun appears more likely, despite continued negotiations to strike a political deal on Tanzania's semi-autonomous islands.

Despite fierce opposition criticism, the government gazette on Wednesday formalized the nullification of the October 25 polls, canceled after the Zanzibar Electoral Commission (ZEC) cited "violations of electoral law".

Tanzania's ruling party candidate John Magufuli won hotly contested presidential elections, officials announced Thursday, but the opposition said the vote was rigged and also claimed victory.

The win by Magufuli with over 58 percent of votes cements the long-running Chama Cha Mapinduzi (CCM) party's firm grip on power, ruling Tanzania since 1977 when two independence-era parties merged.

Tanzania's new leader John Pombe Magufuli rose from humble beginnings to win the presidency of east Africa's most populous nation in the country's hardest ever fought elections.

The win, on his birthday, by the 56-year old former chemistry teacher cements the long-running Chama Cha Mapinduzi (CCM) party's firm grip on power, ruling Tanzania since 1977 when two independence-era parties merged.

Tanzania's ruling party presidential hopeful held the lead Wednesday with around half the votes counted in the country's tightest ever election, though several veteran politicians have lost their seats.

With 133 of 264 constituencies having released results on the third day of counting in east Africa's most populous country, John Magafuli of the long-ruling Chama Cha Mapinduzi (CCM) had won 56.51 percent of votes.

Tanzania's ruling party presidential candidate took an early lead Tuesday as election officials counted votes for a second day, while several key ministers lost their seats.

The polls are expected to be Tanzania's tightest election race ever, with the governing party facing the first major challenge to its dominance in decades.

Votes were being counted Monday in what is expected to be Tanzania's tightest election race ever, with the governing party facing the first major challenge to its dominance in decades.

But the opposition Chadema party have alleged fraud in Sunday's presidential, general and local elections.