About 500 residents from some of Perth's most affluent suburbs are uniting to call for an investigation into WA Planning Minister Rita Saffioti's use of discretionary powers to approve controversial projects.

Protest groups from across the city met in Nedlands on Tuesday night in the hope their combined influence would defend their communities from high-density developments.

The groups are from suburbs ranging from Iluka to Bunbury and include the large and well-organised Save Subi and Save the South Perth Peninsula action groups. They alleged Ms Saffioti misused her legislative powers under the Planning and Development Act 2005 by acting "with no curtailment".

Planning Minister Rita Saffioti. Credit:Nine News Perth

"Discretionary powers are not unfettered," meeting organiser Ian Love said.