Dar es Salaam - A popular Tanzanian rapper said Sunday that he had been arrested over a song allegedly insulting President John Magufuli, seen as increasingly authoritarian and unwilling to brook any dissent. "It is true I am under arrest. Right now I am being taken to the police station," the artist Emmanuel Elibariki, known by his stage name Nay wa Mitego, wrote on his Instagram account.The rapper, known for his political lyrics, and whose videos garner hundreds of thousands of YouTube views, was arrested at a hotel in Morogoro, some 190km from Dar Es Salaam.Morogoro police commander Ulrich Matei told local media that Elibariki was being held for "releasing a song with words that malign the government".In a song released last week, Elibariki raps in Swahili: "Who are you now? Don't you want to listen to advice? Don't you want criticism?"He is addressing someone he calls "a doctor specialising in lancing boils".Wide authoritarian streakThis phrase "lancing boils" has been used repeatedly by Magufuli as he threatens to fire anyone who does not adhere to his policies or orders.Magufuli, whose nickname "Tingatinga" means "bulldozer" in Swahili, swept to power as a no-nonsense, corruption-busting man of the people.But critics see a wide authoritarian streak at the core of his populism, saying he acts on impulse regardless of due process or political niceties, while being intolerant to dissent.Last week he fired his information minister who had criticised Dar es Salaam's regional commissioner Paul Makonda, who stormed into the offices of a local broadcaster with six armed men to demand the airing of a video.Makonda was appointed by Magufuli, who stood up for him over the incident despite a popular outcry.Another line in Elibariki's song, released this month, goes: "I see you handed a club to a madman", widely seen as a reference to Makonda.Since his October election Magufuli has shut down newspapers, banned opposition rallies, switched off live broadcasts of parliamentary sessions and used a draconian "cybercrimes" law to jail critics.On Friday he issued a sharp warning to media critics over their coverage of the Makonda issue."I want to tell media owners to be careful and watch it. If you think you have freedom... not to that extent," Magufuli said.