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.

But a government minister has defended the government's handling of the unrest saying that nobody can state how many were injured.

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.

Foreign Minister Mahmoud Kombo Thabit described what had happened as a few isolated pockets of incidents here and there... our security forces acted very swiftly and decisively to address these situation, he told BBC Focus on Africa TV.

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 casualties.

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.

A UN spokesperson expressed alarm over the situation, calling for restraint among security forces, raising concerns over the reported deaths and injuries linked to the protests.

As unrest continues, protests in significant urban centers like Dar es Salaam exemplify the heightened political tensions in a climactic election period.