She has faced opposition from parts of the army and Magufuli’s allies, and sought to cement her position with an emphatic win, analysts say.
Rights groups say she oversaw a “wave of terror” in the east African nation before the vote, including a string of high-profile abductions that escalated in the final days.
Chadema was barred from taking part in the election and its leader put on trial for treason.
Despite a heavy security presence, election day descended into chaos as crowds took to the streets across the country, tearing down her posters and attacking police and polling stations, leading to an internet shutdown and curfew.
A Chadema spokesman told AFP on Friday that “around 700” people had been killed, based on figures gathered from a network checking hospitals and health clinics.
A security source and diplomat in Dar es Salaam both told AFP that deaths were “in the hundreds”.
Hassan has not made any public statement since the unrest began.
Her Government denies using “excessive force” but has blocked the internet and imposed a tight lockdown and curfew nationwide, making it hard to get any information.
News websites have not been updated since early Wednesday and journalists are not allowed to operate freely in the country.
UN chief Antonio Guterres is “deeply concerned” about the situation in Tanzania, “including reports of deaths and injuries during the demonstrations”, his spokesman said in a statement.
Much public anger has been directed at Hassan’s son, Abdul Halim Hafidh Ameir, accused of overseeing the crackdown.
There have been unconfirmed reports of the army siding with protesters in some places, but army chief Jacob Mkunda came out strongly on Hassan’s side on Thursday, calling the protesters “criminals”.
Foreign Minister Mahmoud Thabit Kombo said Friday that his government had “no figures” on any dead.
“Currently, no excessive force has been used,” he said in an interview with Al Jazeera. “There’s no number until now of any protesters killed.”
– Agence France-Presse
