A former Catholic brother wanted in Australia on 252 charges of child sexual abuse will not know until next month whether he will be extradited from New Zealand.

Bernard Kevin McGrath, 60, is opposing extradition and listened intently during today's hearing at the Christchurch District Court.

New South Wales police have alleged that he sexually assaulted 35 children while working at the Saint John of God Boys Home, Kendall Grange, near Newcastle during the 1970s and 1980s.

Details of today's proceedings cannot be reported as they are subject to a blanket suppression order.

Judge Jane Farish says she will hand down her decision on May 16.