A senior police officer is facing an additional criminal charge after already being accused of sexual connection and indecent assault.

Detective Inspector Kevin Burke's case was called in the High Court at Auckland today where Crown prosecutor Sam McMullan said a new charge of unlawful sexual connection has been laid.

He said the Crown sought to join the new charge to Burke's proceedings, which already included two counts of indecent assault and one charge of sexual connection.

McMullan told the court there was a "considerable number" of police files which need to be investigated to "outline the background of the [alleged] offending".

Burke has pleaded not guilty to the initial three charges and is due to go to trial in February.

Details of Burke's alleged offending remain suppressed.

The 60-year-old Northland cop remains on bail until the case is called in court again later this year.

Burke was stood down last April when the criminal investigation started and was charged in December.

A parallel employment investigation is also under way, as well as a separate inquiry by the Independent Police Conduct Authority.