Detectives from Oxley Local Area Command launched an investigation in 2015 following reports a teenage boy was sexually and indecently assaulted by a man known to him between 1983 and 1986 in Gunnedah.

Following extensive investigations, detectives charged a 56-year-old man on Monday.

He was charged with 20 historical child sex offences, including eight counts of sexual assault (Cat 4) assault and act of indecency person under 16; six counts of sexual assault (Cat 4) assault and indecent act person between 14 and 16; three counts of sexual assault (Cat 3) - person under 16; two counts of sexual assault (Cat 4) incite indecent act person between 14 and 16; and attempt sexual assault (Cat 3) - person under 16 – the charges in place at the time of the alleged offending.

The man remains in custody and will front Tamworth Local Court on August 28.

Oxley Chief Inspector Phil O’Reilly encouraged anyone who has ever been a victim of sexual or indecent assault to report it to police.

“If you have ever been abused, no matter what the circumstance and no matter how long ago it occurred, please get in touch,” Chief Inspector O'Reilly said.

“Our dedicated local detectives work closely with specialist investigators, who are trained to investigate crimes against children, including sexual assault, physical abuse and serious cases of neglect.

“If an adult entrusted with your care took advantage of you, they deserve to be arrested, charged and put before the courts.”

Chief Inspector O’Reilly said all reports are investigated thoroughly by police and victims can also access counselling and support services.

Anyone with concerns about suspected child abuse is being urged to contact local police or call Crime Stoppers on 1800 333 000.