A top Tanzanian official who launched a surveillance squad dedicated to hunting down gay people has been banned by the US from entering the country.

The US state department said Paul Makonda, the administrative chief of the capital Dar es Salaam, was involved in "gross violations of human rights".

His immediate family members have also been barred from visiting the US.

A crackdown on freedom of expression has been on the rise since President John Magufuli came into office in 2015.

Human rights groups also accuse Mr Magufuli of repressing political dissent, detaining human rights activists, and muzzling the media.

US Secretary of State Mike Pompeo tweeted on Friday that Mr Makonda's ban came amidst concern about the "deteriorating" state of human rights in Tanzania.

Today we designated Dar es Salaam Regional Commissioner Paul Christian Makonda as ineligible to enter the U.S. for his involvement in gross violations of #humanrights. We are deeply concerned over deteriorating respect for human rights and rule of law in #Tanzania.

— Secretary Pompeo (@SecPompeo) January 31, 2020

"[Mr Makonda has] also been implicated in the oppression of the political opposition, crackdowns on freedom of expression and association, and the targeting of marginalized individuals," a statement from the US state department said.

It also accused him of being involved in "gross violations of human rights, which include flagrant denial of the right to life, liberty, or the security of persons".

When Mr Makonda - an ally of President Magufuli - launched the anti-gay surveillance force in 2018, he said that he expected international criticism for the move, but added: "I prefer to anger those countries than to anger God."

Homosexual acts are illegal in Tanzania and many gay, lesbian and transgender people are forced to hide their sexuality as a result.

Meanwhile, also on Friday, the US added Tanzania to an expanded list of countries whose citizens are barred from obtaining certain types of immigration visas.