Tanzanian opposition number two Tundu Lissu has been arrested, three days after having called President John Magufuli a "dictator", party sources said.
No reasons were given for the arrest of Lissu, a member of parliament, the Chadema opposition party chief whip and a leading lawyer.

Magufuli, whose nickname 'tingatinga' (bulldozer), swept to power in 2015, presenting himself as a no-nonsense, corruption-busting, man-of-the-people.
However critics see a wide authoritarian streak at the core of his populism. They argue he acts on impulse regardless of due process or political niceties, while being intolerant of any dissent.
Lissu spoke of a "climate of fear which reigns everywhere", accusing Magufuli of constructing "a system based on favouritism, tribalism and regionalism".
Opposition meetings are banned, newspapers have been shut down and journalists and artists have been threatened or received death threats for criticising the administration