Violent protests broke out in Tanzania's biggest city, Dar es Salaam, on Wednesday during an election President Samia Suluhu Hassan is expected to win following the disqualification of the leading opposition candidates.

Internet service was disrupted across the country, monitor group NetBlocks said, as unverified videos of young protesters throwing rocks at security forces and a petrol station in flames circulated on social media.

Hundreds of protesters were marching towards the Selander Bridge that leads to Dar es Salaam's centre, said a witness who asked not to be named.

Witnesses reported violent protests in at least four neighbourhoods of Dar es Salaam, while video from BBC Swahili showed police using tear gas to disperse protesters in another part of the city.

Spokespeople for the government and police did not immediately respond to requests for comment, and Reuters could not confirm the authenticity of the videos on social media.

The vote is being held without the leading opposition party, CHADEMA, whose leader Tundu Lissu is on trial for treason, which he has denied. The electoral commission disqualified CHADEMA in April after it refused to sign an electoral code of conduct.

The commission also disqualified Luhaga Mpina, the presidential candidate for the second-largest opposition party, ACT-Wazalendo, after an objection from the attorney general, leaving only candidates from minor parties taking on Hassan.

OPPOSITION CALLS ELECTION "A CORONATION"

"There is no election in Tanzania. If I may sum up properly, it is a coronation," Deogratius Munishi, CHADEMA's secretary for foreign affairs, told Citizen Television in neighbouring Kenya on Wednesday.

The government has said the election is being conducted fairly and denied allegations of widespread human rights abuses in the run-up, including abductions of opposition figures.

Voters are also choosing members of the country's 400-seat parliament and a president and lawmakers in the semi-autonomous Zanzibar archipelago.

Turnout appeared low at polling stations, which are due to close at 4 pm (1300 GMT). Results are expected within three days.

"I urge all Tanzanians, those who are still at home, to come out and exercise their right and vote and choose their preferred leaders," Hassan said after voting in the administrative capital Dodoma.

She has been traversing the country of around 68-million people to tout her record of expanding transport networks and increasing power generation. 

GOVERNMENT ORDERED PROBE INTO ALLEGED ABDUCTIONS 

Hassan's CCM, whose predecessor party led the struggle for independence for mainland Tanzania in the 1950s, has dominated national politics since it was founded in 1977.

Hassan, one of only two female heads of state in Africa, won plaudits after coming to power in 2021 for easing repression of political opponents and censorship that proliferated under her predecessor, John Magufuli, who died in office.

But in the last two years, rights campaigners and opposition candidates have accused the government of unexplained abductions of its critics.

This month, the country's former ambassador to Cuba, now a fierce critic of the government, was taken from his home by unknown assailants, his family said. Police said they were investigating.

Hassan has said her government is committed to respecting human rights and last year ordered an investigation into the reports of abductions. No official findings have been made public.