A former childcare worker in Australia has been charged with sexually abusing 91 children in what has been described as one of the worst child sex abuse cases in the country’s history.

The 45-year-old man has been charged with 1,623 separate offences, including 136 counts of rape, 110 counts of sexual intercourse with a child under 10 and 613 counts of producing child exploitation material, the Australian Federal Police (AFP) said on Tuesday.

The alleged crimes were carried out at 12 different childcare centres in Sydney, Brisbane and overseas between 2007 and 2022, police said.

The man, who police said passed background checks required for his job, is alleged to have recorded himself abusing his victims, all of whom were pre-pubescent girls.

Police said they believe that all 87 Australian children recorded in the child exploitation material have been identified and authorities are working with international partners to identify four children abused overseas.

Investigators had been searching for the man since discovering a collection of child exploitation images and videos circulating on the dark web in 2014.

The accused man, from the Gold Coast in Queensland, has been in custody since he was arrested and charged with a number of child exploitation offences in August 2022.

The man, who has not been named, is scheduled to face Brisbane Magistrates Court on August 21.

“While I am extremely proud of law enforcement’s persistence and their unwavering dedication to identify this alleged offender, and stop further abuse, this is chilling news,” AFP Northern Assistant Commissioner Justine Gough said.

“It is with a heavy heart that the AFP and other law enforcement dedicate so much time and resources to prevent and take action against individuals who commit heinous crimes against children.”

New South Wales state police Assistant Commissioner Michael Fitzgerald described the case as “one of the most horrific cases of alleged child abuse our detectives have seen”.

“Alongside our partner agencies, we are absolutely committed to prosecuting anyone who goes after our community’s most vulnerable,” Fitzgerald said. (Al Jazeera)