Ties between the two countries soured in 2018 when Australia became the first country to publicly ban China's Huawei from its 5G network and worsened when Australia last year called for an inquiry into the origins of the novel coronavirus.

In a statement to the UN Human Rights Council in Geneva, China alleged that the detention centres "fall short of adequate medical conditions where a large number of immigrants, refugees and asylum seekers have been detained over a long period of time or even indefinitely, and their human rights have been violated".

It did not specify any locations, describing them as "third countries".

Asylum seekers intercepted at sea en route to Australia are sent for "processing" to Papua New Guinea or to the South Pacific island of Nauru.

Australia's Department of Foreign Affairs and Trade did not immediately respond to a request for comment outside normal working hours.

China itself has long faced accusations that it operates detention centres, with UN experts and rights groups estimating it has detained more than a million people in its Xinjiang region, mostly Uighurs and other Muslim minorities, in a vast system of camps.

China has described the camps as vocational centres designed to combat extremism.

"We urge Australia to immediately close down all offshore detention centres and take concrete steps to protect the rights of immigrants, refugees and asylum seekers, especially children," China said in its statement, which it submitted on behalf of a group of unnamed countries.

It also called on Australia to carry out "comprehensive and fair investigations" into reported cases of "serious war crimes" committed by Australian troops overseas.

An Australian inquiry published in November said Australian special forces were suspected of killing 39 unarmed prisoners and civilians in Afghanistan between 2005 and 2016, drawing criticism from China's foreign ministry.

Australian Associated Press