Tanzania's electoral commission has dismissed opposition allegations of fraud in Wednesday’s general election.
The head of the National Elections Commission, Semistocles Kaijage, said claims of fake ballot papers were unsubstantiated.
The main opposition presidential candidate, Tundu Lissu of the Chadema party, claimed that there were widespread irregularities and his agents were prevented from accessing polling stations.
The opposition also said there were irregularities in the semi-autonomous archipelago of Zanzibar, where unrest marred early voting on 27 October.
Local media have said voting passed off peacefully across the mainland and Zanzibar. Results from the presidential elections are not expected for days.
After the internet monitor Net Blocks reported "widespread internet disruption" that affected Twitter, WhatsApp, Instagram and Google services, ProtonVPN - an open source VPN provider - said on Twitter that the authorities were now trying to block VPN services.
President John Magufuli, who has been accused of clamping down on public freedoms, is seeking a second five-year term.