According to civil society groups, at least 40 individuals have been illegally detained in Russia's southern region since December, reports that the State Department deemed "credible."

At least two people are reported to have been tortured to death, according to St Petersburg-based rights group LGBT Network.

The allegations follow 2017 reports that more than 100 LGBT individuals were arrested and tortured with some killed in the predominantly Muslim Russian republic.

"I can confirm that two gay men were killed while being tortured," LGBT Network head Igor Kochetkov was reported as saying by the Moscow Times on Monday.

"We are deeply disturbed by credible reports out of Chechnya about renewed attacks against individuals perceived to be members of the LGBTI community," State Department spokesperson Robert Palladino said in a statement.

"We call on Russia to live up to its international obligations and commitments and its own constitution, and launch an immediate investigation into these human rights abuses," Palladino added.

Alvi Karimov, a spokesman for Chechen leader Ramzan Kadyrov, claimed that the latest reports were, "complete lies and don't have an ounce of truth in them," according to Moscow-based Interfax news agency.

Kremlin-backed Kadyrov has shrugged off allegations of LGBT persecutions, with his spokesperson repeatedly claiming that no persecution of gays could have occurred in Chechnya because there are no gay people there.

Australian Associated Press