Updated

A woman wanted in Chile on kidnapping charges dating back to Chile's 1973-1990 military dictatorship is expected to appear in a Sydney court on Wednesday for an extradition hearing.

Chile's Supreme Court requested the extradition of Adriana Rivas in 2014. She was wanted for her alleged role in the 1976 killing of a Communist Party leader who was held in a secret prison before he was suffocated and thrown into the ocean.

Australian Attorney-General Christian Porter, who has responsibility for extraditions, said Rivas was arrested in Sydney on Tuesday at the request of Chile.

"This individual is wanted to face prosecution in the Republic of Chile for aggravated kidnapping offences," Chester said in a statement on Tuesday.

"As the matter is ongoing, it would not be appropriate to comment further," Chester added.

Information on an attorney was not immediately available on Wednesday.

Rivas was an assistant to Manuel Contreras, the head of the DINA secret police during Gen. Augusto Pinochet's dictatorship.

She moved to Australia in 1978 but was detained during a visit to Chile in 2006. Rivas was released after some months on probation and fled to Australia.

Rivas has been working as a part-time nanny and a cleaner in Sydney's wealthy eastern suburbs, Australian Broadcasting Corp. reported.

Chilean-born lawyer Adriana Navarro said the extradition process had been complex.

"There's been a number of technical obstacles along the way because the Chilean system of law is completely different to the Australian system," Navarro said. "That's why it's taken five years."

Navarro said the Chilean diaspora in Australia was ecstatic about Rivas' arrest.

"There's about 45,000 Chileans here and the majority of us, including myself, came to Australia fleeing the Pinochet dictatorship," Navarro said.

In 2014, Rivas told Australia's Special Broadcasting Service that she was innocent of the charges, but defended the use of torture in Chile at the time as necessary.

"They had to break the people — it has happened all over the world, not only in Chile," she said in Spanish.