The proposed Bunbury Forum expansion will go before the Bunbury City Council at tonight's committee meeting where councillors are expected to discuss the affect a major department store could have on the central business district.

The owner of the Forum, Atlas Point Pty Ltd, has sought to expand the centre to provide an additional 16,000sq m of retail floor space including a two-story national department store.

The council will have to consider the implications, primarily the future development of the CBD, if it supports a major retailer at the Forum.

The council is expected to defer the matter until it has assessed other preferred locations around the city, namely the CBD, for a department store.

Independent planning consultants Shrapnel Urban Planning said there needed to be an assessment of the potential impact on Bunbury retailers as a whole.

The council is required to make a recommendation which will go to the WA Planning Commission for the final decision.