Simon Davies, 65, touched down at Sydney airport on Friday night after four NSW detectives travelled to The Hague to escort him back to Australia.

He was later charged with 18 child sexual and indecent assault offences, allegedly committed across Sydney between 1981 and 1987.

In a brief hearing at Parramatta Local Court on Saturday, Davies did not apply for bail and it was formally refused as he appeared via video link.

He will remain in police custody while awaiting his next court date in early June.

Davies has been wanted in NSW since September 2016, more than five years after police received a referral outlining historic child sex offence allegations from 1981 to 1983.

He was arrested at Rotterdam police station under a Interpol Red Notice in December 2019 and was held in custody as federal agencies sought his extradition.

Detective Superintendent Stacey Maloney, commander of the child abuse and sex crimes squad, said police had worked tirelessly to ensure justice for the alleged victims.

"This has been a complex and exhaustive investigation for police, who have spent nearly 10 years investigating these matters and a further 16 months navigating the extradition process and the subsequent challenges imposed on worldwide travel due to COVID-19," she said.

"It is a testament to the strength, bravery and patience of the victims, together with the determination and dedication of police, that charges have now been laid in relation to these alleged crimes."

The four detectives who flew to the Netherlands to escort Davies have entered hotel quarantine, where they will remain for 14 days before returning to work.

Australian Associated Press