China is 'in a league of its own' on human rights violations, Pompeo says

China is “in a league of its own” when it comes to human rights violations, the US secretary of state, Mike Pompeo, said on Wednesday as he unveiled the state department’s annual report on human rights around the world.

Related: 'If you enter a camp, you never come out': inside China's war on Islam

Pompeo also highlighted abuses in Iran, South Sudan and Nicaragua but singled out Beijing for its mass detention of members of Muslim minority groups in the Xinjiang region.

China, often seen as the main strategic adversary of the United States in the long term and locked in thorny trade talks with Washington, “is in a league of its own when it comes to human rights violations”, he said.

The report said that authorities in the region have arbitrarily detained 800,000 to possibly more than 2 million Uighurs, ethnic Kazakhs and other Muslims in internment camps designed to erase religious and ethnic identities.

“For me, you haven’t seen things like this since the 1930s,” said Michael Kozak, the head of the state department’s human rights and democracy bureau.

“Rounding up, in some estimations ... in the millions of people, putting them into camps, and torturing them, abusing them and trying to basically erase their culture and their religion and so on from their DNA. It’s just remarkably awful.”

Kozak said China had initially denied there even were camps, and is now saying “there are camps, but they’re some kind of labor training camps and it’s all very voluntary”.

The report came hours after a senior official in Xinjiang hinted that the system of internment centres – which China describes as vocational training centres – may one day be phased out.

“In general there will be fewer and fewer students in the centres. If one day our society doesn’t need them, the education and training centres will disappear,” said Shohrat Zakir, the governor of the region and its most senior Uighur official.

Zakir’s comments come after months of mounting international criticism, and signal what could be a new phase in China’s campaign in Xinjiang, as the costs prove unsustainable for local governments and a significant portion of the population passes through the camps.

The state department report said government officials in China had claimed the camps were needed to combat terrorism, separatism and extremism. However, international media, human rights organizations and former detainees have reported that security officials in the camps abused, tortured and killed some detainees, it said.

“It is one of the most serious human rights violations in the world today,” said Kozak.

Related: US alters Golan Heights designation from 'Israeli-occupied' to 'Israeli-controlled'

Pompeo also said the Iranian government had killed more than 20 people and arrested thousands without due process for protesting for their rights “continuing a pattern of cruelty the regime has inflicted on the Iranian people for the last four decades”.

In South Sudan, he said that military forces inflicted sexual violence against civilians based on their political allegiances and ethnicity, while in Nicaragua, peaceful protesters had faced sniper fire and government critics had “faced a policy of exile, jail or death”.

The report also revised its usual description of the Golan Heights from “Israeli-occupied” to “Israeli-controlled”.

A separate section on the West Bank and Gaza Strip, areas that Israel captured along with the Golan Heights in a 1967 war in the Middle East, also did not refer to those territories as being “occupied”, or under “occupation”.