Dar es Salaam regional commissioner Monday launched an anti-gay crackdown, threatening to arrest people suspected of being homosexuals.
"I have information about the presence of many homosexuals in our province," Paul Makonda told reporters on Monday, calling on citizens to begin reporting homosexuals for round-ups to begin next week.
Under British colonial-era laws homosexuality is illegal in Tanzania, with same-sex acts between men punishable by a maximum life sentence.
"These homosexuals boast on social networks," said Makonda, a fervent Christian and loyal ally of President John Magufuli.
"Give me their names," he demanded. "My ad hoc team will begin to get their hands on them next Monday."
Makonda said he expected criticism from outsiders for his hardline stance but added: "I prefer to anger those countries than to anger God."
Makonda said homosexual behaviour "tramples on the moral values of Tanzanians and our two Christian and Muslim religions".
Anti-homosexual sentiment is rife in Tanzania, forcing most gays, lesbians and other sexual minorities to live in secrecy.
Political rhetoric against homosexuality has increased since Magufuli's 2015 election.
Last year the president said that everybody should condemn homosexuality, "even cows" and soon after his government threatened to arrest or deport gay rights activists.
Three South Africans were subsequently expelled for allegedly advocating for same-sex marriage.
AIDS clinics have also been shut down under Magafuli, accused of "promoting" homosexuality, while he has encouraged women to abandon birth control and have more babies.