Tanzania results 'mockery of democracy': opposition

"We are calling for the intervention by a credible body to oversee another fresh election," said John Kitoka.

"That is a slap on the people's face, and people are very angry, and very soon we are going to announce our reaction that could also include calling for national protests," he said.

Chadema's monitors in hospitals and health clinics have reported "no less than 800 people" killed by security forces in protests that broke out on election day, Kitoka said.

These figures could not be independently verified, partly due to a total internet blackout and a ban on journalists operating around the country.

Kitoka said the electoral commission's figures of an 87-percent turnout in the election were "simply a joke".

"What happened on the 29th of October was simply not an election so whatever comes out of it is illegitimate," he said.

Foreign Minister Mahmoud Thabit Kombo said Friday that his government had "no figures" on any dead.

"Currently, no excessive force has been used," he said in an interview with Al Jazeera.