Louis Theroux has been lauded by viewers for delivering a “compelling” if “uncomfortable” look at sex trafficking in his latest documentary.

The television star’s new series, Dark States, sees Theroux investigate drugs, sex trafficking and murder.

In Sunday night’s instalment of the BBC Two programme he spends time with American women working in the sex industry and explores the dynamic between prostitute and pimp.

Many viewers said on social media that the gritty series was a tough watch.

“A brutal yet brilliant programme. The way women are exploited is horrific but the truth needs to be told, however uncomfortable,” one person said on Twitter.

“Watching Louis Theroux is uncomfortable tonight. Living is complex,” said another.

One impressed viewer tweeted: “#DarkStates is compelling viewing.

“Hard to imagine all the human carnage/damage caused by sex trafficking. Heartbreaking.”

Fans flooded Twitter with posts praising the way Theroux handled a tricky subject.

The documentary-maker was called “a master”, “a British institution” and even “a don”.

And one fan wrote: “Louis Theroux is to humans what David Attenborough is to animals.”

The third instalment of Theroux’s series, Murder In Milwaukee, airs next Sunday at 9pm on BBC Two.