Foreign election observers are expected to commend Tanzanian authorities for a largely peaceful voting day but raise concerns about the levels of transparency in the country's tightly contested polls.
The observers are expected to issue their first official report about Sunday's election at a press conference in Dar es Salaam on Tuesday afternoon.
"Voting day was generally peaceful across the country but there are concerns about the lack of transparency in some aspects of the process," a member of the European Union team of election observers told The EastAfrican on condition of anonymity because of the sensitivity of the matter.
John Pombe Magufuli, the candidate of the ruling Chama cha Mapinduzi (CCM) party remains ahead of his closest challenger, Edward Lowassa of Chadema party in official results announced by the National Electoral Commission (NEC) but the opposition candidate on Monday accused NEC of selectively releasing results in a manner likely to facilitate fraud.
Chadema officials also wrote to the Inspector General of Police on Monday to demand the release of 191 officials arrested from its official tally centres in Dar es Salaam during raids on Sunday night.
In Zanzibar, the semi-autonomous archipelago of Tanzania, police fired teargas to disperse opposition supporters after CUF candidate Seif Sharif Hamad declared himself the winner of the island's presidency ahead of CCM candidate and incumbent, Dr Ali Mohamed Shein.
The tensions have continued into Tuesday. Police in Muleba town, in northern Tanzania, have fired teargas to disperse crowds demonstrating against parliamentary results announced in the area.
With 120 out of 264 constituencies reporting on Tuesday morning, CCM had won 77 seats, CUF 18 while Chadema 24 (matching total from last Parliament) and others 2. More results are expected in the course of the day and NEC has promised to release final results by Thursday.