A teacher at a private school on Sydney’s north shore has been charged with possessing child abuse material after he left his mobile phone at a swimming pool, police say.

Detectives were called to Knox Grammar on Monday afternoon after “a large number of child abuse images” were found on a phone left at the aquatic centre.

Nick Warby, 30, was arrested and taken to Hornsby police station while officers searched his home and seized a number of electronic devices.

It is also alleged drugs – including ice and GHB – were found in the man’s car.

Knox headmaster Scott James in a letter to parents said the teacher had been removed from his duties at the aquatic centre.

“A colleague discovered inappropriate internet images on a mobile phone which we believe belongs to the staff member,” James wrote in Tuesday’s letter.

“Police were alerted. They have advised us that there is currently no suggestion the images relate to Knox boys or swim centre students.”

Warby appeared at Hornsby local court on Tuesday afternoon and was granted bail.

He is due back in court on 27 August.

The 30-year-old is the director of aquatic sports at Knox, according to his LinkedIn profile, and has been in the role since early 2017.

The teacher has described himself as a “friendly and enthusiastic educator with a passion for promoting sport and physical activity amongst young people”.

Warby has been a volunteer with Surf Life Saving Australia and the NSW Rural Fire Service.