Tanzanian President Samia Suluhu Hassan is being sworn in shortly for a second term following an election marred by violent protests and rejected by the opposition as a sham.

The inauguration ceremony is being held at a military parade grounds in the capital, Dodoma, in an event closed to the public but broadcast live by the state-run TBC.

Samia was declared the winner on Saturday with 98% of the vote. She faced little opposition with key rival candidates either imprisoned or barred from running.

International observers have raised concerns about the transparency of the election and its violent aftermath, with hundreds of people reportedly killed and injured.

The authorities have sought to downplay the scale of the violence. It has been difficult to obtain information from the country or verify the death toll, amid a nationwide internet shutdown in place since election day

In her victory speech, Samia said the poll was "free and democratic" and described the protesters as "unpatriotic".

Opposition leaders and activists say hundreds were killed in clashes with security forces. The opposition Chadema party told the AFP news agency that it had recorded "no less than 800" deaths by Saturday, while a diplomatic source in Tanzania told the BBC there was credible evidence that at least 500 people had died.

The UN human rights office earlier said there were credible reports of at least 10 deaths in three cities.