Adelaide's Catholic Archbishop Philip Wilson has lost his appeal against a magistrate's refusal to quash a charge of concealing child abuse at the hands of a New South Wales priest.

Wilson is the most senior Catholic clergyman to be charged with covering up child sexual abuse.

Earlier this year, the Catholic Archbishop of Adelaide Philip Wilson asked the New South Wales Supreme Court to dismiss a criminal prosecution alleging he failed to report child abuse allegations.

The abuse was alleged to have been carried out by Father Jim Fletcher during the 1970s in the Maitland-Newcastle Catholic Diocese.

At the time Wilson was an assistant parish priest in East Maitland and worked with the now-dead paedophile priest.

Police allege that between 2004 and 2006, Wilson had information which might have helped police secure Fletcher's conviction.

Wilson applied for a permanent stay of proceedings to have the matter thrown out of court, but that was denied by a local court magistrate in February 2016.

That prompted an appeal to the NSW Supreme Court, which has today been dismissed.

Justice Monika Schmidt ruled that the evidence was capable of supporting the prosecution's case.

Wilson's legal team had previously argued the child sexual abuse cover-up charge was invalid, as there was no evidence the offence he was accused of concealing ever happened.