Police in Tanzania have arrested the chairman of the main opposition party in the wake of disputed polls.
Freeman Mbowe was detained, along with two other Chadema leaders, for planning violent protests, according to the police.
Official results released on Friday showed President John Magufuli was re-elected with 84% of the vote.
But the opposition said Wednesday's poll was fraudulent and called for peaceful demonstrations.
Chadema's presidential candidate Tundu Lissu told the BBC's Newsday programme that he had also heard of the arrest of party leaders in other parts of the country.
Over the weekend, the leaders of Chadema and another opposition party, ACT-Wazalendo, urged their supporters to come out in large numbers to peacefully protest and demand fresh elections.
As of 09:00 local time (06:00 GMT) no demonstrations had been reported in mainland Tanzania or Zanzibar, the BBC's Athuman Mtulya reports from the main city Dar es Salaam.
Police have threatened to use force to detain anyone who takes part in street demonstrations.
Tanzania's National Electoral Commission has dismissed the opposition's claims of fraud.
And on Friday an observer mission from the East African Community said that the election was "conducted in a regular manner".