Don't block mosques, says Luke Foley

NSW Opposition Leader Luke Foley says blocking the construction of mosques could drive radical preaching underground.

Mr Foley says decisions by local authorities to reject approvals for mosques will be "counter-productive" in fostering good relationships with Muslims in Australia.

His comments come after the fatal shooting of police accountant Curtis Cheng outside Parramatta police headquarters by 15-year-old Farhad Jabar Khalil Mohammad.

Mohammad reportedly attended a lecture by extremist group Hizb ut-Tahrir at a mosque on Friday before shooting Mr Cheng.

"Often decisions by councils to block approvals for Mosques are counter-productive because then you see unregulated, underground prayer halls where you just don't know what's being preached," Mr Foley told reporters on Monday.

He said more should be done to help Muslim leaders set up "above ground" places of religious worship that preach mainstream Islam.

Mr Foley says he will work with Prime Minister Malcolm Turnbull and NSW Premier Mike Baird to combat radicalisation.