NSW Liberal MP Rory Amon has been charged with a number of child sex offences.

Mr Amon, MP for Pittwater in Sydney's Northen Beaches, is accused of five counts of sexual intercourse with a person between 10 and 14 and two counts of attempting sexual intercourse with a person between 10 and 14.

The 35-year-old has also been charged with two counts of indecently assaulting a person under 16 and committing an act of indecency with a person under 16.

In June 2022, detectives attached to Northern Beaches Police Area Command started an investigation following reports of an alleged sexual assault in Mona Vale in July 2017.

Police were told a teenage boy was allegedly sexually assaulted by a man who was known to him at an address in Mona Vale.

In March 2023, Strike Force NOORAL was established to investigate the incident.

Following extensive inquiries, Mr Amon was arrested at Manly Police Station about 6am today.

Mr Amon was given strict conditional bail to appear at Manly Local Court on September 18.

Mr Amon, a former lawyer, was elected to parliament last year.

He is currently the shadow assistant minister for the portfolios of infrastructure, transport and roads, and youth.

Before entering state politics, he sat on Northern Beaches Council, representing Narrabeen Ward from 2017 to 2021 and Pittwater Ward from 2021 to 2023.

News of the charges broke as NSW Police Minister Yasmin Catley and Commissioner Karen Webb were giving evidence at a budget estimates hearing.

"This is news to me," Ms Catley said.

Commissioner Webb said she would take a question about the processes in relation to Mr Amon's charging on notice.

The state opposition has cancelled a media conference on estimates planned for Friday afternoon.