Population drain from regional areas will force the abolition of one federal electorate in NSW and a redistribution of electoral boundaries before the next election.

The Australian Electoral Commission has said the growing population of Western Australia justifies an additional seat in Parliament for that state. However, the total number of seats in the House of Representatives will remain at 150.

Political pundits believe the biggest effects will be felt in the upper Hunter Valley and lower North Coast of NSW where enrolments have fallen the most dramatically.

But the redrawing of boundaries will effect the sparsely populated central division of NSW and even push the southern Sydney seat of Macarthur, held by Liberal Russell Matheson, south from Campbelltown and into the southern Highlands.

A Labor Party source said a potential redrawing of the boundaries of Hunter is not expected to pose a threat to long-time MP Joel Fitzgibbon.