Hundreds of people have been killed in Tanzania during three days of protests following Wednesday's general election, the country's main opposition party has said.

A Chadema party spokesperson told the AFP news agency that "around 700" people had died in clashes with security forces. A nationwide internet shutdown is making it difficult to verify reports of deaths.

The BBC has spoken to a diplomatic source in Tanzania who said there was credible evidence that at least 500 people had died.

Demonstrations have been taking place in major cities with young protesters denouncing the vote as unfair as key opposition figures were barred from running against President Samia Suluhu Hassan.

Protests have continued on Friday in the main city Dar es Salaam - in the neighbourhoods of Salasala, Yombo and Tegeta - as demonstrators defied warnings from the country's army chief to end the unrest.

"Some people went to the streets on 29 October and committed criminal acts. These are criminals and the criminal acts should be stopped immediately," Gen Jacob John Mkunda said on state TV on Thursday, adding that the army had "controlled the situation".

The government has sought to play down the scale of the violence - and the authorities have extended a curfew in a bid to quell the unrest.

It has been difficult for journalists and human rights groups to check the reports of deaths because of the internet shutdown.

Hospitals in the country have been refusing to give out information when asked about causalities.

A source at one referral hospital in Dar es Salaam told the BBC it had been overwhelmed with casualties since Thursday.

The source added that they had heard this was also the case at other public hospitals in the city where morgues were reportedly full.

The UN has called on the East African nation's security forces to refrain from using unnecessary or disproportionate force.

"We are alarmed by the deaths and injuries that have occurred in the ongoing election-related protests in Tanzania. Reports we have received indicate that at least 10 people were killed," Reuters quoted the UN human rights spokesperson Seif Magango as saying earlier on Friday.

The BBC understands that ambassadors from several foreign embassies have also engaged the Tanzanian government to urge restraint from security forces in policing the protests.

By late afternoon on Friday, the electoral commission had announced results from about 80 of the country's 272 regions, according to the state broadcaster TBC.

The BBC understands that international observers have reported an incredibly low turnout during polling on Wednesday.

President Samia is expected to win the vote under the ruling Chama Cha Mapinduzi (CCM) party, which has governed the country since independence in 1961.

Official results are expected on Saturday.

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