Hundreds of people have been killed in Tanzania over the past three days of protests, the country's main opposition party has said.

The exact number of those killed has not been known because internet services have been cut off.

A spokesman for the opposition party Chadama told AFP that "about 700 people" had been killed in clashes with security forces. The BBC's diplomatic sources said "at least 500 people" had been killed.

The Tanzanian government has said the violence is not widespread. It has decided to extend the curfew.

Most of the protesters were young people who took to the streets to protest the unfairness of the election.

They said the government had suppressed democracy by barring major opposition figures from the election.

Ahead of the election, rights activists have denounced the government's worsening crackdown.

A report by Amnesty International shows that arbitrary arrests, disappearances, torture and killings are taking place.