A group of door knockers working for charity have allegedly threatened to gang-rape a female neighbour when they were turned away from a Byford property on Monday evening.

The group have attended a number of Byford and Mundijong properties over the last week and have claimed to fundraise for Oxfam.

The matter has been referred to WA Police.

They have reportedly become aggressive when refused donations by residents and in one instance, it was alleged the group threatened a female homeowner with rape.

A witness said they had reviewed their CCTV footage after hearing about the incident from their neighbour.